Datasets:

morteza

/

cogtext

like 0

10.3109/07420528.2010.504992

Chronobiology international

Chronobiol Int

Prior night sleep duration is associated with psychomotor vigilance in a healthy sample of police academy recruits.

Aviation, military, police, and health care personnel have been particularly interested in the operational impact of sleep restriction and work schedules given the potential severe consequences of making fatigue-related errors. Most studies examining the impact of sleep loss or circadian manipulations have been conducted in controlled laboratory settings using small sample sizes. This study examined whether the relationship between prior night sleep duration and performance on the psychomotor vigilance task could be reliably detected in a field study of healthy police academy recruits. Subjects (N = 189) were medically and psychiatrically healthy. Sleep-wake activity was assessed with wrist actigraphy for 7 days. Subjects performed the psychomotor vigilance task (PVT) for 5 min on a personal digital assistant (PDA) device before and after their police academy workday and on comparable times during their days off. Mixed-effects logistic regression was used to estimate the probability of having > or =1 lapse on the PVT as a function of the previous night sleep duration during the 7 days of field testing. Valid estimates of sleep duration were obtained for 1082 nights of sleep. The probability of a lapse decreased by 3.5%/h sleep the night prior to testing. The overall probability of having a lapse decreased by 0.9%/h since awakening, holding hours of sleep constant. Perceived stress was not associated with sleep duration or probability of performance lapse. These findings demonstrate the feasibility of detecting sleep and circadian effects on cognitive performance in large field studies. These findings have implications regarding the daytime functioning of police officers.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Undersea & hyperbaric medicine : journal of the Undersea and Hyperbaric Medical Society, Inc

Undersea Hyperb Med

Hyperbaric stress in divers and non-divers: neuroendocrine and psychomotor responses.

This study compared neuroendocrine and psychomotor responses in divers (D, n = 11) and non-divers (ND, n = 9) following 30-minute hyperbaric and decompression stress to 180, 300 and 450 kPa. Venous blood was drawn pre-dive and at 20 and 60 minutes post-dive and analyzed for norepinephrine (NE), epinephrine (E), tryptophan (TRP), cortisol (COR), growth hormone (GH), adrenocorticotrophic hormone (ACTH) and prolactin (PRL). Reaction time was assessed using a psychomotor vigilance task. There was no difference between groups, across time or among levels of hyperbaric stress, for NE, E, TRP or GH. Small decreases over time in COR were noted. ACTH was significantly higher for ND at 20 minutes following 180 kPa and after 60 minutes for 450 kPa exposure. PRL increased significantly more for ND, and changes from baseline following 450 kPa exposure were moderately related (r = 0.52) to the significant slowing of reaction time at 20 minutes (296 +/- 55 msec) and 60 minutes (277 +/- 35 msec) compared with baseline (247 +/- 22 msec), although PRL returned to baseline levels faster than reaction time. It was concluded that for the stress hormones measured, PRL may provide some indication of the adaptation involved with repeated hyperbaric stress, but its relationship to changes in reaction time was weak.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.bbr.2010.07.041

Behavioural brain research

Behav Brain Res

Rat psychomotor vigilance task with fast response times using a conditioned lick behavior.

Investigations into the physiological mechanisms of sleep control require an animal psychomotor vigilance task (PVT) with fast response times (<300 ms). Rats provide a good PVT model since whisker stimulation produces a rapid and robust cortical evoked response, and animals can be trained to lick following stimulation. Our prior experiments used deprivation-based approaches to maximize motivation for operant conditioned responses. However, deprivation can influence physiological and neurobehavioral effects. In order to maintain motivation without water deprivation, we conditioned rats for immobilization and head restraint, then trained them to lick for a 10% sucrose solution in response to whisker stimulation. After approximately 8 training sessions, animals produced greater than 80% correct hits to the stimulus. Over the course of training, reaction times became faster and correct hits increased. Performance in the PVT was examined after 3, 6 and 12 h of sleep deprivation achieved by gentle handling. A significant decrease in percent correct hits occurred following 6 and 12 h of sleep deprivation and reaction times increased significantly following 12 h of sleep deprivation. While behaviorally the animals appeared to be awake, we observed significant increases in EEG delta power prior to misses. The rat PVT with fast response times allows investigation of sleep deprivation effects, time-on-task and pharmacological agents. Fast response times also allow closer parallel studies to ongoing human protocols.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.3357/asem.2756.2010

Aviation, space, and environmental medicine

Aviat Space Environ Med

Time of day effects on neurobehavioral performance during chronic sleep restriction.

Chronic nocturnal sleep restriction results in accumulation of neurobehavioral impairment across days. The purpose of this study was to determine whether time of day modulates the effects of sleep restriction on objective daytime performance deficits and subjective sleepiness across days of chronic sleep restriction. There were N = 90 healthy adults (21-49 yr; 38 women) who participated in a 14-d laboratory protocol involving randomization to 1 of 18 schedules of restricted nocturnal sleep with and without a diurnal nap for 10 consecutive days. The total time available for daily sleep ranged from 4.2 h to 8.2 h across conditions. Performance lapses on the psychomotor vigilance test (PVT) and subjective sleepiness were measured each day every 2 h during scheduled wakefulness. Nonlinear mixed-effects regression was used to test the hypothesis that there would be an interaction between time of day and the accumulation (slope across days) of neurobehavioral sleepiness. In agreement with earlier studies, less sleep time resulted in faster accumulation of deficits across days. Time of day significantly affected this relationship for both PVT lapses and subjective sleepiness. The build-up rate of cumulative neurobehavioral deficits across days was largest at 0800 and became progressively smaller across the hours of the day, especially between 1600 and 2000. Following 8 d of sleep restricted to 4 h/d, subjects averaged 8.3 more PVT performance lapses at 0800 than at 1800. This study provides evidence that the circadian system has a substantial modulatory effect on cumulative impairment from chronic sleep restriction and that it facilitates a period of relatively protected alertness in the late afternoon/early evening hours when nocturnal sleep is chronically restricted.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.apergo.2010.06.010

Applied ergonomics

Appl Ergon

Performance on a simple response time task: Is sleep or work more important for miners?

The purpose of the current study was to investigate the impact of work- and sleep-related factors on an objective measure of response time in a field setting. Thirty-five mining operators working 12-h shift patterns completed daily sleep and work diaries, wore activity monitors continuously and completed palm-based psychomotor vigilance tests (palmPVT) at the start and end of each shift. Linear mixed models were used to test the main effects on response time of roster, timing of test, sleep history and prior wake. The time at which the test occurred was a significant predictor of response time (F₃(,)₄₀₃(.)₄ = 6.72, p < .01) with the end of night shifts being associated with significantly slower response times than the start of night shifts, and the start or end of day shifts. Further, the amount of sleep obtained in the 24h prior to the test was also a significant predictor of response time (F₃(,)₄₀₇(.)₀ = 3.05, p < .01). The results suggest that, as expected, the end of night shift is associated with changes in response time indicative of performance impairments. Of more interest however is that immediate sleep history was also predictive of changes in response time with lower amounts of prior sleep related to slower response times. The current data provides further evidence that sleep is a primary mediator of performance, independent of roster pattern.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1186/1744-9081-6-47

Behavioral and brain functions : BBF

Behav Brain Funct

Meditation acutely improves psychomotor vigilance, and may decrease sleep need.

A number of benefits from meditation have been claimed by those who practice various traditions, but few have been well tested in scientifically controlled studies. Among these claims are improved performance and decreased sleep need. Therefore, in these studies we assess whether meditation leads to an immediate performance improvement on a well validated psychomotor vigilance task (PVT), and second, whether longer bouts of meditation may alter sleep need. The primary study assessed PVT reaction times before and after 40 minute periods of mediation, nap, or a control activity using a within subject cross-over design. This study utilized novice meditators who were current university students (n = 10). Novice meditators completed 40 minutes of meditation, nap, or control activities on six different days (two separate days for each condition), plus one night of total sleep deprivation on a different night, followed by 40 minutes of meditation.A second study examined sleep times in long term experienced meditators (n = 7) vs. non-meditators (n = 23). Experienced meditators and controls were age and sex matched and living in the Delhi region of India at the time of the study. Both groups continued their normal activities while monitoring their sleep and meditation times. Novice meditators were tested on the PVT before each activity, 10 minutes after each activity and one hour later. All ten novice meditators improved their PVT reaction times immediately following periods of meditation, and all but one got worse immediately following naps. Sleep deprivation produced a slower baseline reaction time (RT) on the PVT that still improved significantly following a period of meditation. In experiments with long-term experienced meditators, sleep duration was measured using both sleep journals and actigraphy. Sleep duration in these subjects was lower than control non-meditators and general population norms, with no apparent decrements in PVT scores. These results suggest that meditation provides at least a short-term performance improvement even in novice meditators. In long term meditators, multiple hours spent in meditation are associated with a significant decrease in total sleep time when compared with age and sex matched controls who did not meditate. Whether meditation can actually replace a portion of sleep or pay-off sleep debt is under further investigation.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.3109/07420528.2010.488958

Chronobiology international

Chronobiol Int

Interindividual differences in neurobehavioral performance in response to increasing homeostatic sleep pressure.

Neurobehavioral function deteriorates with increasing homeostatic sleep pressure during wakefulness. It has been claimed that some individuals exhibit a quicker rate of such deterioration than others, thus being more vulnerable than others to the detrimental impact of increasing homeostatic sleep pressure. Evidence supporting the claim, however, has been limited by methodological issues. To overcome these limitations, the current study used a 12-calendar-day, 28-h forced desynchrony (FD) protocol (sleep:wake period = 1:2) to study individual differences in the rate of change in neurobehavioral performance with increasing homeostatic sleep pressure. Neurobehavioral performance was assessed with a psychomotor vigilance task and a serial addition subtraction task. A significant performance decline on both tasks was revealed within as short as 17 h of wakefulness. The rates of decline of individual performance trajectories were, however, not different from the group average rate. This suggests that individuals are not differentially vulnerable to the detrimental impact of increasing homeostatic sleep pressure.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.apergo.2010.04.005

Applied ergonomics

Appl Ergon

The relationship between subjective and objective sleepiness and performance during a simulated night-shift with a nap countermeasure.

The aim of the present study was to investigate the relationship between perceived and actual sleepiness and performance during a simulated night-shift that included a 30-min night-nap as an on-duty sleepiness countermeasure. Twenty-four healthy young adults (nine males, fifteen females) participated in a repeated measures design comprising two experimental conditions: no night-nap and 30-min night-nap. Both groups were given a 2-h prophylactic afternoon sleep opportunity (1500-1700 h). Measures of subjective sleepiness (Stanford Sleepiness Scale, Karolinska Sleepiness Scale and Visual Analogue Scale), objective sleepiness (sleep latency tests), objective performance (Symbol-Digit Substitution Task) and reaction time (Psychomotor Vigilance Task) were taken before the night-nap (0230 h) and at several intervals post-nap. Time-series correlation analyses indicated that subjective sleepiness was less correlated with objective sleepiness and objective performance when participants were given a 30-min night-nap. However subjective sleepiness and reaction time performance was strongly correlated in both conditions, and there was no significant difference between the nap and no-nap conditions. Consistent with previous research, results of the present study indicate that subjective and objective indicators of sleepiness and performance may not always correspond, and this relationship may be reduced by the inclusion of a night-nap.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine

J Clin Sleep Med

Gender differences in obstructive sleep apnea and treatment response to continuous positive airway pressure.

Whether gender differences exist in clinical manifestations of obstructive sleep apnea (OSA) and whether women's responses to continuous positive airway pressure (CPAP) are similar to those of men are critical areas of exploration in sleep disordered breathing. This exploratory analysis addressed these questions by examining gender differences over a wide range of clinical outcomes at baseline and in response to CPAP in participants with severe OSA. Data from 152 men and 24 women who participated in a multicenter CPAP effectiveness study were analyzed. Gender differences in functional status (functional outcomes of sleep questionnaire, sickness impact profile), daytime sleepiness (epworth sleepiness scale, multiple sleep latency test), mood disturbance (profile of mood states), apnea symptoms (multivariable apnea prediction index), and neurobehavioral performance (psychomotor vigilance task) were examined. Treatment response was examined by the change in each outcome from baseline to 3 months after treatment. Despite similar age, body mass index, and apnea-hypopnea index, women reported significantly lower functional status, more subjective daytime sleepiness, higher frequency of apnea symptoms, more mood disturbance, and poorer neurobehavioral performance compared to men at baseline. CPAP treatment significantly improved functional status and relieved symptoms for both genders. The magnitude of improvement in each clinical outcome did not vary by gender. Women with OSA showed greater impairment in daytime functioning and symptoms than men. Both genders benefit from CPAP treatment. Adequately powered studies considering possible referral and response bias are necessary to examine gender differences in OSA clinical manifestations and response to CPAP treatment.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1177/1740774510368298

Clinical trials (London, England)

Clin Trials

Treatment of obesity with extension of sleep duration: a randomized, prospective, controlled trial.

The prevalence of chronic sleep deprivation is increasing in modern societies with negative health consequences. Recently, an association between short sleep and obesity has been reported. To assess the feasibility of increasing sleep duration to a healthy length (approximately 7(1/2) h) and to determine the effect of sleep extension on body weight. To examine the long-term effects of sleep extension on endocrine (leptin and ghrelin) and immune (cytokines) parameters, the prevalence of metabolic syndrome, body composition, psychomotor vigilance, mood, and quality of life. One hundred-fifty obese participants who usually sleep less than 6(1/2) h, are being randomized at a 2:1 ratio to either an Intervention or to a Comparison Group. They are stratified by age (above and below 35) and the presence or absence of metabolic syndrome. During the first 12 months (Efficacy Phase) of the study, participants are evaluated at bi-monthly intervals: the Intervention Group is coached to increase sleep by at least 30-60 min/night, while the Comparison Group maintains baseline sleep duration. In the second (Effectiveness) phase, participants converge into the same group and are asked to increase (Comparison Group) or maintain (Intervention Group) sleep duration and are evaluated at 6-month intervals for an additional 3 years. Non-pharmacological and behavior-based interventions are being utilized to increase sleep duration. Endocrine, metabolic, and psychological effects are monitored. The sleep, energy expenditure, and caloric intake are assessed by activity monitors and food recall questionnaires. At yearly intervals, body composition, abdominal fat, and basal metabolic rate are measured by dual energy X-ray absorptiometry (DXA), computerized tomography (CT), and indirect calorimetry, respectively. As of January 2010, 109 participants had been randomized, 64 to the Intervention Group and 45 to the Comparison Group (76% women, 62% minorities, average age: 40.8 years; BMI: 38.5 kg/m(2)). Average sleep duration at screening was less than 6 h/night, 40.3 h/week. A total of 28 Intervention and 22 Comparison participants had completed the Efficacy Phase. The study is not blinded and the sample size is relatively small. This proof-of-concept study on a randomized sample will assess whether sleep extension is feasible and whether it influences BMI. Clinical Trials 2010; 7: 274-285. http://ctj.sagepub.com.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine

J Clin Sleep Med

Number of lapses during the psychomotor vigilance task as an objective measure of fatigue.

This study examined how well the Psychomotor Vigilance Task (PVT) performance was related to subjective measures of fatigue. In order to study subjects presenting with a wide range of fatigue symptoms, we studied healthy individuals as well as patients with varying severity of obstructive sleep apnea. We also examined if the PVT/fatigue relationship could be influenced by depressive symptoms. Forty-eight participants had their sleep monitored with polysomnography. Fatigue was assessed by Multidimensional Fatigue Symptom Inventory-short form (MFSI-sf). Depressed mood was assessed by the Center for Epidemiologic Studies-Depression (CES-D) Scale. After sleep monitoring and psychological assessments, the 10-minute PVT was administered. The main outcome variable was the PVT lapse count. Simple correlations and hierarchical linear regression were used to examine the association between age, body mass index (BMI), sleep variables, apnea hypopnea index (AHI), oxygen desaturation index (ODI), CES-D, fatigue, and PVT. The PVT lapse count was significantly associated with MFSI-sf physical fatigue (r = 0.324, p = 0.025). In hierarchical regression (full model R2 = 0.256, p = 0.048), higher BMI (p = 0.038), and higher MFSI-sf physical fatigue (p= 0.040) were independent predictors of the PVT lapse count. Age, AHI, ODI, and CES-D were unrelated to the PVT lapse count. In conclusion, the findings suggest that even after controlling for age, BMI, depression, and apnea severity, physical fatigue is associated with the PVT lapse.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2010.00823.x

Journal of sleep research

J Sleep Res

Sleep restriction for the duration of a work week impairs multitasking performance.

It is important to develop shift schedules that minimise the chance for sleep-related human error in safety-critical domains. Experimental data on the effects of sleep restriction (SR) play a key role in this development work. In order to provide such data, we conducted an experiment in which cognitively demanding and long-duration task performance, simulating task performance at work, was measured under SR and following recovery. Twenty healthy male volunteers, aged 19-29 years, participated in the study. Thirteen of them had first two baseline days (8-h sleep opportunity per day), then five SR days (4-h sleep) and finally two recovery days (8-h sleep). Seven controls were allowed to sleep for 8 h each night. On each experimental day, multitask performance was tested in 50-min sessions, physiological sleepiness was evaluated during multitask performance using electroencephalogram (EEG)/electrooculogram (EOG) recordings, and psychomotor vigilance task performance and Karolinska Sleepiness Scale were recorded. Sleep-wake rhythm was monitored throughout the experiment. The multitask performance progressively deteriorated as a result of prolongation of the SR and the time spent on the task. The effect was significant at group level, but individual differences were large: performance was not markedly deteriorated in all participants. Similar changes were observed also in EEG/EOG-defined sleepiness. The recovery process of performance and sleepiness from the SR continued over the two recovery sleep opportunities. In all, our findings emphasise the importance of shift systems that do not restrict sleep for several consecutive days.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.33549/physiolres.931895

Physiological research

Physiol Res

Effects of different sleep restriction protocols on sleep architecture and daytime vigilance in healthy men.

Sleep is regulated by complex biological systems and environmental influences, neither of which is fully clarified. This study demonstrates differential effects of partial sleep deprivation (SD) on sleep architecture and psychomotor vigilance task (PVT) performance using two different protocols (sequentially) that each restricted daily sleep to 3 hours in healthy adult men. The protocols differed only in the period of sleep restriction; in one, sleep was restricted to a 3-hour block from 12:00 AM to 3:00 AM, and in the other, sleep was restricted to a block from 3:00 AM to 6:00 AM. Subjects in the earlier sleep restriction period showed a significantly lower percentage of rapid-eye-movement (REM) sleep after 4 days (17.0 vs. 25.7 %) and a longer latency to the onset of REM sleep (L-REM) after 1 day (78.8 vs. 45.5 min) than they did in the later sleep restriction period. Reaction times on PVT performance were also better (i.e. shorter) in the earlier SR period on day 4 (249.8 vs. 272 ms). These data support the view that earlier-night sleep may be more beneficial for daytime vigilance than later-night sleep. The study also showed that cumulative declines in daytime vigilance resulted from loss of total sleep time, rather than from specific stages, and underscored the reversibility of SR effects with greater amounts of sleep.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1360-0443.2009.02880.x

Addiction (Abingdon, England)

Addiction

The effects of binge drinking on college students' next-day academic test-taking performance and mood state.

To assess the effects of binge drinking on students' next-day academic test-taking performance. A placebo-controlled cross-over design with randomly assigned order of conditions. Participants were randomized to either alcoholic beverage [mean = 0.12 g% breath alcohol concentration (BrAC)] or placebo on the first night and then received the other beverage a week later. The next day, participants were assessed on test-taking, neurocognitive performance and mood state. A total of 196 college students (>or=21 years) recruited from greater Boston. The trial was conducted at the General Clinical Research Center at the Boston Medical Center. The Graduate Record Examinations(c) (GREs) and a quiz on a lecture presented the previous day measured test-taking performance; the Neurobehavioral Evaluation System (NES3) and the Psychomotor Vigilance Test (PVT) measured neurocognitive performance; and the Profile of Mood States (POMS) measured mood. Test-taking performance was not affected on the morning after alcohol administration, but mood state and attention/reaction-time were affected. Drinking to a level of 0.12 g% BrAC does not affect next-day test-taking performance, but does affect some neurocognitive measures and mood state.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/33.4.523

Sleep

Sleep

Randomized controlled trial comparing flexible and continuous positive airway pressure delivery: effects on compliance, objective and subjective sleepiness and vigilance.

Positive airway pressure (PAP) treatment for obstructive sleep apnea (OSA) can be limited by suboptimal compliance. C-Flex technology (Philips Respironics, PA, USA) reduces pressure during expiration, aiming to improve comfort and therefore compliance. This may be of particular relevance to patients requiring high pressures. Many studies thus far have suffered from design limitations and small sample sizes. This study aimed to compare compliance with C-Flex and CPAP, as well as analyzing objective and subjective sleepiness and vigilance. Three-month, double-blinded, parallel-arm randomized controlled trial. A university-based sleep laboratory. 76 consecutive patients with severe OSA (mean +/- SD AHI 60.2 +/- 32.9 events/hour, ESS 13.6 +/- 4.5/24, BMI 35.6 +/- 7.8 kg/m2), without significant cardiac, respiratory, psychiatric, or sleep comorbidities. Patients were randomized to C-Flex (dip level 2) or CPAP. Patients underwent titration with C-Flex/CPAP (mean pressure 11.6 cm H2O). Modified maintenance of wakefulness tests (mod-MWT), psychomotor vigilance tasks (PVT) and questionnaires were administered at baseline and after one and 3 months. Median compliance was 5.51 and 5.89 h/night in the C-Flex and CPAP groups respectively (P = 0.82). There were no significant differences between groups in terms of PVT reaction time, subjective sleepiness, sleep quality, health-related quality of life, or treatment comfort. There was no significant difference between the groups regarding the change in mod-MWT sleep latency values. In patients with severe OSA both CPAP and C-Flex resulted in substantial improvements in sleepiness, vigilance, and quality of life. The use of C-Flex did not result in greater compliance, and neither treatment appeared superior.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/33.4.481

Sleep

Sleep

Circadian and wake-dependent influences on subjective sleepiness, cognitive throughput, and reaction time performance in older and young adults.

To assess circadian and homeostatic influences on subjective sleepiness and cognitive performance in older adults when sleep and waking are scheduled at different times of day; to assess changes in subjective sleepiness and cognitive performance across several weeks of an inpatient study; and to compare these findings with results from younger adults. Three 24-h baseline days consisting of 16 h of wakefulness and an 8-h sleep opportunity followed by 3-beat cycles of a 20-h forced desynchrony (FD) condition; 18 20-h "days," each consisting of 13.33 h of scheduled wakefulness and 6.67 h of scheduled sleep opportunity. Intensive Physiological Monitoring Unit of the Brigham and Women's Hospital General Clinical Research Center. 10 healthy older adults (age 64.00 +/- 5.98 y, 5 females) and 10 healthy younger adults (age 24.50 +/- 3.54 y, 5 females). Wake episodes during FD scheduled to begin 4 h earlier each day allowing for data collection at a full range of circadian phases. Subjective sleepiness, cognitive throughput, and psychomotor vigilance assessed every 2 h throughout the study. Core body temperature (CBT) data collected throughout to assess circadian phase. Older subjects were less sleepy and performed significantly better on reaction time (RT) measures than younger subjects. Decrements among younger subjects increased in magnitude further into the experiment, while the performance of older subjects remained stable. Our findings demonstrate that the waking performance and alertness of healthy older subjects are less impacted by the cumulative effects of repeated exposure to adverse circadian phase than that of young adults. This suggests that there are age-related changes in the circadian promotion of alertness, in the wake-dependent decline of alertness, and/or in how these 2 regulatory systems interact in healthy aging.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.3109/07420521003648604

Chronobiology international

Chronobiol Int

Circadian rhythms of psychomotor vigilance, mood, and sleepiness in the ultra-short sleep/wake protocol.

Despite its advantages as a chronobiological technique, the ultra-short sleep/wake protocol remains underutilized in circadian rhythm research. The purpose of this study was to examine circadian rhythms of psychomotor vigilance (PVT), mood, and sleepiness in a sample (n=25) of healthy young adults while they adhered to a 3 h ultra-short sleep/wake protocol. The protocol involved 1 h sleep intervals in darkness followed by 2 h wake intervals in dim light, repeated for 50-55 h. A 5 min PVT test was conducted every 9 h with the standard metrics of mean reaction time (RT; RT(mean)), median RT (RT(med)), fastest 10% of responses (RT(10fast)), and reciprocal of the 10% slowest responses (1/RT(10slow)). Subjective measures of mood and sleepiness were assessed every 3 h. A cosine fit of intra-aural temperature, assessed three times per wake period, established the time of the body temperature minimum (T(min)). Mood, sleepiness, and PVT performances were expressed relative to individual means and compared across eight times of day and twelve 2 h intervals relative to T(min). Significant time-of-day and circadian patterns were demonstrated for each of the PVT metrics, as well as for mood and sleepiness. Most mood subscales exhibited significant deterioration in day 2 of the protocol without alteration of circadian pattern. However, neither sleepiness nor performance was worse on the second day of observation compared to the first day. These data provide further support for the use of the ultra-short sleep/wake protocol for measurement of circadian rhythms.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/33.2.197

Sleep

Sleep

PVT lapses differ according to eyes open, closed, or looking away.

A lapse during the psychomotor vigilance task (PVT) is usually defined as a response longer than 500 ms; however, it is currently unknown what psychobiological phenomena occur during a lapse. An assessment of what a participant is doing during a lapse may depict varying levels of "disengagement" during these events and provide more insight into the measurement of both a lapse and sleepiness. Repeated measures. Participants underwent extended 30-min PVT sessions twice, at 22:00 and 04:00, under: (i) typical non-distractive laboratory conditions, and (ii) an additional distractive condition. Twenty-four healthy young adults (mean age: 23.2 y +/- 2 y; range 21-25 y [12 m; 12 f]) without any sleep or medical problems and without any prior indication of daytime sleepiness. One night of sleep loss. Distraction comprised a TV located at 90 degrees in the visual periphery showing a popular TV program. For the non-distraction condition, the TV was turned off. Video data (bird's-eye and frontal view) were used to classify each lapse (> or = 500 ms) as occurring with eyes open (EO), eyes closed (EC), or due to a head turn (HT). EO lapses were more prevalent, with all lapses (EO, EC, and HT) increasing with sleepiness. There was a significant effect of distraction for HT lapses which was exacerbated when sleepy. For lapse duration there was little effect of sleepiness for EO lapses but a significant effect for EC and HT. The 95% confidence intervals for lapse duration and associated behavior showed those lapses greater than 2669 ms were 95% likely to be EC, whereas those 500-549 ms were 95% likely to be EO. Response times of 1217 ms had a 50:50 probability of being EO:EC. Discriminating the varying causes of lapses whether due to visual inattention (eyes open), microsleep (eyes closed), or distraction (head turn) may provide further insight into levels of disengagement from the PVT and further insight into developing sleepiness.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1007/s00420-010-0515-5

International archives of occupational and environmental health

Int Arch Occup Environ Health

Effects of nocturnal aircraft noise on cognitive performance in the following morning: dose-response relationships in laboratory and field.

Nocturnal aircraft noise disturbs sleep and impairs recuperation. We investigated in laboratory and field studies whether noise-induced sleep fragmentation is associated with performance impairments in a psychomotor vigilance task (PVT) and a memory search task. In the laboratory, 112 participants were exposed to aircraft noise during 9 consecutive nights. In the field, 64 participants were examined during 9 consecutive nights in the vicinity of Cologne/Bonn airport. Reaction time, signal detection performance and subjective task load were recorded. Dose-response relationships showed significant, linear impairments in reaction times. In the laboratory, reaction time in PVT increased with 0.13 ms/dB equivalent noise level (LAeq) plus 0.02 ms/noise event. In the field study, reaction time increased with 0.3 ms/dB LAeq. Participants worked significantly less accurate after nocturnal noise exposure. Influences of LAeq and number of noise events on daytime performance were small but consistent and significant, stressing the potential public health impact of nocturnal noise exposure.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1164/rccm.200908-1307OC

American journal of respiratory and critical care medicine

Am J Respir Crit Care Med

Modafinil effects during acute continuous positive airway pressure withdrawal: a randomized crossover double-blind placebo-controlled trial.

Continuous positive airway pressure (CPAP) use is associated with reduced motor vehicle accidents in patients with obstructive sleep apnea (OSA). However, interruption of CPAP therapy is common and is associated with a decline in daytime function. We hypothesized that the wakefulness promoter, modafinil, would ameliorate this decline. Patients were admitted to the laboratory for three consecutive nights. CPAP was used for the first night, followed by a baseline day, and was then withdrawn for the two subsequent nights (nasal airflow monitored). On each of the mornings after the two CPAP withdrawal nights, patients received 200 mg modafinil or placebo (n = 21) in a randomized, double-blind, crossover design. Treatment periods were separated by a 5-week washout. Driving simulator performance, neurocognitive performance, and subjective alertness were measured by the AusEd driving simulator, psychomotor vigilance task, and Karolinska Sleepiness Scale, respectively. During CPAP withdrawal, severe sleep-disordered breathing was evident and administration of modafinil improved simulated driving performance (steering variability, P < 0.0001; mean reaction time, P <or= 0.0002; lapses, P <or= 0.01 on a concurrent task), psychomotor vigilance task (mean 1/reaction time and lapses, both P <or= 0.0002), and subjective sleepiness (P <or= 0.01). Modafinil prevented the decline in simulated driving performance, neurocognitive performance, and subjective sleepiness in patients with OSA with acutely interrupted CPAP therapy. Clinical trial registered with the Australian New Zealand Clinical Trials Registry at www.anzctr.org.au (ACTRN12606000027516).

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine

J Clin Sleep Med

Treatment of sleep disorders after traumatic brain injury.

Determine whether treatment of sleep disorders identified in brain injured adults would result in resolution of those sleep disorders and improvement of symptoms and daytime function. Prospective evaluation of unselected traumatic brain injury patients with nocturnal polysomnography (NPSG), multiple sleep latency test (MSLT), Epworth Sleepiness Scale (ESS), and neuropsychological testing including Psychomotor Vigilance Test (PVT), Profile of Mood States (POMS), and Functional Outcome of Sleep Questionnaire (FOSQ) before and after treatment with continuous positive airway pressure (CPAP) for obstructive sleep apnea (OSA), modafinil (200 mg) for narcolepsy and posttraumatic hypersomnia (PTH), or pramipexole (0.375 mg) for periodic limb movements in sleep (PLMS). Three academic medical centers. Fifty-seven (57) adults > or = 3 months post traumatic brain injury (TBI). Abnormal sleep studies were found in 22 subjects (39%), of whom 13 (23%) had OSA, 2 (3%) had PTH, 3 (5%) had narcolepsy, 4 (7%) had PLMS, and 12 had objective excessive daytime sleepiness with MSLT score < 10 minutes. Apneas, hypopneas, and snoring were eliminated by CPAP in OSA subjects, but there was no significant change in MSLT scores. Periodic limb movements were eliminated with pramipexole. One of 3 narcolepsy subjects and 1 of 2 PTH subjects had resolution of hypersomnia with modafinil. There was no significant change in FOSQ, POMS, or PVT results after treatment. Treatment of sleep disorders after TBI may result in polysomnographic resolution without change in sleepiness or neuropsychological function.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.sleep.2009.07.012

Sleep medicine

Sleep Med

Treatment of elderly primary insomnia patients with EVT 201 improves sleep initiation, sleep maintenance, and daytime sleepiness.

Two doses of EVT 201, a partial positive allosteric modulator of the GABA(A) system, were evaluated in elderly primary insomnia patients with daytime sleepiness. Participants were 149 elderly patients with DSM-IV primary insomnia including evidence of daytime sleepiness (53 males, 96 females; mean age 71.3yrs, range 65-86yrs). A randomized, multicentre, double-blind, placebo-controlled, parallel-group design was used to assess the hypnotic efficacy of EVT 201 1.5 and 2.5mg during seven consecutive nights. Polysomnography (PSG) was performed on nights 1, 6 and 7 of treatment. Daytime assessments on Day 8 included the multiple sleep latency test (MSLT), Rey Auditory Verbal Learning Test (RAVLT), Psychomotor Vigilance Task (PVT) and the Karolinska Sleepiness Scale (KSS). The primary endpoint was total sleep time (TST) and the key secondary endpoint was mean MSLT latency. Compared to placebo, EVT 201 1.5 and 2.5mg increased TST (30.9, 56.4min, respectively; p=0.0001, p<0.0001); reduced wake after sleep onset (WASO; -15.2, -36.1min, respectively; p=0.014, p<0.0001); reduced latency to persistent sleep (LPS; -15.9, -19.9min, respectively; p=0.009, p=0.001). The 2.5mg dose also reduced WASO in hours 5-8 (-16.3min, p=0.001). Both doses also improved subjective sleep quality and usual subjective efficacy measures. A significantly longer mean MSLT latency was observed on Day 8 with both doses, compared to placebo (2min increase; p=0.03, both doses). The PVT, RAVLT, and POMS did not differ among treatment groups. No serious or unexpected treatment emergent adverse events were noted. EVT 201 improved PSG measures of sleep onset and sleep maintenance and significantly reduced daytime physiological sleep tendency. These findings suggest that treatment of primary insomnia in older patients has the potential to improve daytime sleepiness as well as sleep.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.neuroimage.2009.11.020

NeuroImage

Neuroimage

Imaging brain fatigue from sustained mental workload: an ASL perfusion study of the time-on-task effect.

During sustained periods of a taxing cognitive workload, humans typically display time-on-task (TOT) effects, in which performance gets steadily worse over the period of task engagement. Arterial spin labeling (ASL) perfusion functional magnetic resonance imaging (fMRI) was used in this study to investigate the neural correlates of TOT effects in a group of 15 subjects as they performed a 20-min continuous psychomotor vigilance test (PVT). Subjects displayed significant TOT effects, as seen in progressively slower reaction times and significantly increased mental fatigue ratings after the task. Perfusion data showed that the PVT activates a right lateralized fronto-parietal attentional network in addition to the basal ganglia and sensorimotor cortices. The fronto-parietal network was less active during post-task rest compared to pre-task rest, and regional CBF decrease in this network correlated with performance decline. These results demonstrate the persistent effects of cognitive fatigue in the fronto-parietal network after a period of heavy mental work and indicate the critical role of this attentional network in mediating TOT effects. Furthermore, resting regional CBF in the thalamus and right middle frontal gyrus prior to task onset was predictive of subjects' subsequent performance decline, suggesting that resting CBF quantified by ASL perfusion fMRI may be a useful indicator of performance potential and a marker of the level of fatigue in the neural attentional system.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/32.10.1393

Sleep

Sleep

The variable response-stimulus interval effect and sleep deprivation: an unexplored aspect of psychomotor vigilance task performance.

The Psychomotor Vigilance Task (PVT) contains variable response-stimulus intervals (RSI). Our goal is to investigate the effect of RSI on performance to determine whether sleep deprivation affects the ability to attend to events across seconds and whether this effect is independent of impairment in sustaining attention across minutes, as measured by time on task. A control group following their normal sleep routines and 3 groups exposed to 54 hours of total sleep deprivation performed a 10-minute PVT every 6 hours for 9 total test runs. Sleep deprivation occurred in a sleep laboratory with continuous behavioral monitoring; the control group took the PVT at home. Eighty-four healthy sleepers (68 sleep deprivation, 16 controls; 22 women; aged 18-35 years). Across groups, as the RSI increased from 2 to 10 seconds, mean RT was reduced by 69 milliseconds (main effect of RSI, P < 0.001). There was no interaction between the sleep deprivation and RSI effects. As expected, there was a significant interaction of sleep deprivation and time on task for mean RT (P = 0.002). Time on task and RSI effects were independent. Parallel analyses of percentage of lapses and percentage of false starts produced similar results. We demonstrate that the cognitive mechanism of attention responsible for response preparation across seconds is distinct from that for maintaining attention to task performance across minutes. Of these, only vigilance across minutes is degraded by sleep deprivation. Theories of sleep deprivation should consider how this pattern of spared and impaired aspects of attention may affect real-world performance.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2009.00782.x

Journal of sleep research

J Sleep Res

Daytime sleepiness, psychomotor performance, waking EEG spectra and evoked potentials in women with severe premenstrual syndrome.

We assessed daytime sleepiness using objective and subjective measures in women with severe premenstrual syndrome (PMS) compared with women without significant premenstrual symptoms. Nine women with severe PMS and eight controls (aged 18-40 years) completed a laboratory-based daytime protocol including the maintenance of wakefulness test (MWT), psychomotor vigilance task (PVT), quantitative waking electroencephalogram (EEG), auditory and visual event-related potentials (ERPs), and sleepiness and mood scales during the mid-follicular and late-luteal (premenstrual) phases of the menstrual cycle. In association with increased perceived sleepiness, fatigue and other premenstrual symptoms in the late-luteal phase, women with PMS performed more poorly on the PVT, with increased lapses and slower reaction times (P < 0.05), compared with the follicular phase and controls. However, there were no significant group or menstrual phase differences in latency to sleep on the MWT. Waking spectral EEG power and ERP measures also did not differentiate PMS women when symptomatic. Both groups of women displayed increased spectral power in the delta/theta frequencies (2-6 Hz) and fast alpha frequency (11-12 Hz) in the late-luteal phase relative to the follicular phase. Trait-like differences were apparent in that women with PMS had increased beta1 (12-16 Hz) power and smaller P300 amplitude than controls in both menstrual cycle phases. Our findings indicate that women with severe PMS are subjectively sleepy and fatigued, and show psychomotor slowing when symptomatic compared with when they are symptom-free and compared with controls. However, the ability to maintain wakefulness under soporific conditions, spectral properties of waking EEG and cognitive processing do not vary in synchrony with premenstrual symptoms.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1186/1471-2202-10-105

BMC neuroscience

BMC Neurosci

Preliminary evidence that both blue and red light can induce alertness at night.

A variety of studies have demonstrated that retinal light exposure can increase alertness at night. It is now well accepted that the circadian system is maximally sensitive to short-wavelength (blue) light and is quite insensitive to long-wavelength (red) light. Retinal exposures to blue light at night have been recently shown to impact alertness, implicating participation by the circadian system. The present experiment was conducted to look at the impact of both blue and red light at two different levels on nocturnal alertness. Visually effective but moderate levels of red light are ineffective for stimulating the circadian system. If it were shown that a moderate level of red light impacts alertness, it would have had to occur via a pathway other than through the circadian system. Fourteen subjects participated in a within-subject two-night study, where each participant was exposed to four experimental lighting conditions. Each night each subject was presented a high (40 lx at the cornea) and a low (10 lx at the cornea) diffuse light exposure condition of the same spectrum (blue, lambda(max) = 470 nm, or red, lambda(max) = 630 nm). The presentation order of the light levels was counterbalanced across sessions for a given subject; light spectra were counterbalanced across subjects within sessions. Prior to each lighting condition, subjects remained in the dark (< 1 lx at the cornea) for 60 minutes. Electroencephalogram (EEG) measurements, electrocardiogram (ECG), psychomotor vigilance tests (PVT), self-reports of sleepiness, and saliva samples for melatonin assays were collected at the end of each dark and light periods. Exposures to red and to blue light resulted in increased beta and reduced alpha power relative to preceding dark conditions. Exposures to high, but not low, levels of red and of blue light significantly increased heart rate relative to the dark condition. Performance and sleepiness ratings were not strongly affected by the lighting conditions. Only the higher level of blue light resulted in a reduction in melatonin levels relative to the other lighting conditions. These results support previous findings that alertness may be mediated by the circadian system, but it does not seem to be the only light-sensitive pathway that can affect alertness at night.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2008.00716.x

Journal of sleep research

J Sleep Res

The sensitivity of a PDA-based psychomotor vigilance task to sleep restriction in 10-year-old girls.

The impact of sleep restriction on sustained attention in children has not been well quantified. To address this shortcoming, this study tested the sensitivity of a 5-min personal digital assistant-psychomotor vigilance task (PDA-PVT) to sleep restriction in 14 female children [mean (SD) age = 10.6 +/- 0.3 years]. The children underwent PDA-PVT trials at regular intervals both before and after a sleep restriction (5 h time-in-bed) and a control (10 h time-in-bed) condition. Sleep restriction was associated with longer mean response times and increased number of lapses. These results are consistent with findings in the adult literature suggesting an association between inadequate sleep and impaired functioning. In conclusion, the 5-min PDA-PVT is sensitive to sleep restriction in pre-adolescent female children supporting the utility of the PDA-PVT for examining the impact of sleep deprivation on daytime functioning in children.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.neubiorev.2009.07.009

Neuroscience and biobehavioral reviews

Neurosci Biobehav Rev

Sleepiness as a need for sleep: when is enough, enough?

This review considers the relationship between sleep need and sleepiness. In healthy adults, objective measures of sleepiness (e.g. Multiple Sleep Latency Test; Psychomotor Vigilance Test) and subjective indices (e.g. Stanford Sleepiness Scale) often poorly inter-correlate and have been seen as orthogonal dimensions. This is perhaps not surprising as the methodology of these tests is quite different in, for example, their duration, testing environment, whether they are experimenter versus participant-paced, and the understanding and expectancy of participants. It is argued, here, that 'sleepiness', the 'propensity to fall asleep' and the 'need for sleep' are not synonymous, but qualitatively different. They may represent different positions on a dimension ranging from essential to non-essential sleep/sleepiness, and the position on this dimension is detected to varying extents by the different measures. As these tests can detect - and perhaps induce - levels of sleepiness which would be undetectable by, and of little concern to people under everyday situations, they can reveal a sleepiness having the potential to be misinterpreted as sleep debt.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/32.7.905

Sleep

Sleep

Neurobehavioral performance in young adults living on a 28-h day for 6 weeks.

Performance on many cognitive tasks varies with time awake and with circadian phase, and the forced desynchrony (FD) protocol can be used to separate these influences on performance. Some performance tasks show practice effects, whereas the Psychomotor Vigilance Task (PVT) has been reported not to show such effects. We aimed to compare performance on the PVT and on an addition test (ADD) across a 6-week FD study, to determine whether practice effects were present and to analyze the circadian and wake-dependent modulation of the 2 measures. A 47-day FD study conducted at the Brigham and Women's Hospital General Clinical Research Center. Eleven healthy adults (mean age: 24.4 years, 2 women). For 2 baseline days and across 6 weeks of FD, we gave a test battery (ADD, PVT, self-rating of effort and performance) every 2 hours. During FD, there was a significant (P < 0.0001) improvement in ADD performance (more correct calculations completed), whereas PVT performance (mean reaction time, fastest 10% reaction times, lapses) significantly (P < 0.0001) declined week by week. Subjective ratings of PVT performance indicated that subjects felt their performance improved across the study (P < 0.0001), but their rating of whether they could have performed better with greater effort did not change across the study (P > 0.05). The decline in PVT performance suggests a cumulative effect of sleep loss across the 6-week study. Subjects did not accurately detect their declining PVT performance, and a motivational factor could not explain this decline.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1080/07420520903044364

Chronobiology international

Chronobiol Int

Blue light exposure reduces objective measures of sleepiness during prolonged nighttime performance testing.

This study examined the effects of nocturnal exposure to dim, narrowband blue light (460 nm, approximately 1 lux, 2 microW/cm2), compared to dim broad spectrum (white) ambient light ( approximately 0.2 lux, 0.5 microW/cm2), on subjective and objective indices of sleepiness during prolonged nighttime performance testing. Participants were also exposed to a red light (640 nm, approximately 1 lux, 0.7 microW/cm2) placebo condition. Outcome measures were driving simulator and psychomotor vigilance task (PVT) performance, subjective sleepiness, salivary melatonin, and electroencephalographic (EEG) activity. The study had a repeated-measures design, with three counterbalanced light conditions and a four-week washout period between each condition. Participants (n = 8) maintained a regular sleep-wake schedule for 14 days prior to the approximately 14 h laboratory study, which consisted of habituation to light conditions followed by neurobehavioral performance testing from 21:00 to 08:30 h under modified constant-routine conditions. A neurobehavioral test battery (2.5 h) was presented four times between 21:00 and 08:30 h, with a 30 min break between each. From 23:30 to 05:30 h, participants were exposed to blue or red light, or remained in ambient conditions. Compared to ambient light exposure, blue light exposure suppressed EEG slow wave delta (1.0-4.5 Hz) and theta (4.5-8 Hz) activity and reduced the incidence of slow eye movements. PVT reaction times were significantly faster in the blue light condition, but driving simulator measures, subjective sleepiness, and salivary melatonin levels were not significantly affected by blue light. Red light exposure, as compared to ambient light exposure, reduced the incidence of slow eye movements. The results demonstrate that low-intensity, blue light exposure can promote alertness, as measured by some of the objective indices used in this study, during prolonged nighttime performance testing. Low intensity, blue light exposure has the potential to be applied to situations where it is desirable to increase alertness but not practical or appropriate to use bright light, such as certain occupational settings.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/32.3.311

Sleep

Sleep

Banking sleep: realization of benefits during subsequent sleep restriction and recovery.

Determine whether sleep extension (a) improves alertness and performance during subsequent sleep restriction and (b) impacts the rate at which alertness and performance are restored by post-restriction recovery sleep. Participants were randomly assigned to an Extended (10 h time in bed [TIB]) or Habitual TIB [mean (SD) hours = 7.09 (0.7)] sleep group for one week, followed by 1 Baseline (10 hours or habitual TIB), 7 Sleep Restriction (3 h TIB), and 5 Recovery Sleep nights (8 h TIB). Performance and alertness tests were administered hourly between 08:00-18:00 during all in-laboratory phases of the study. Residential sleep/performance testing facility. Twenty-four healthy adults (ages 18-39) participated in the study. Extended vs. habitual sleep durations prior to sleep restriction. Psychomotor vigilance task (PVT) lapses were more frequent and modified maintenance of wakefulness (MWT) sleep latency was shorter in the Habitual group than in the Extended group across the sleep restriction phase. During the Recovery phase, PVT speed rebounded faster (and PVT lapsing recovered significantly after the first night of recovery sleep) in the Extended group. No group differences in subjective sleepiness were evident during any phase of the study. The extent to which sleep restriction impairs objectively measured alertness and performance, and the rate at which these impairments are subsequently reversed by recovery sleep, varies as a function of the amount of nightly sleep obtained prior to the sleep restriction period. This suggests that the physiological mechanism(s) underlying chronic sleep debt undergo long-term (days/weeks) accommodative/adaptive changes.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.sleep.2008.07.013

Sleep medicine

Sleep Med

A pilot study of sleep, cognition, and respiration under 4 weeks of intermittent nocturnal hypoxia in adult humans.

A pilot study to examine the effects of intermittent nocturnal hypoxia on sleep, respiration and cognition in healthy adult humans. Participants were eight healthy, non-smoking subjects (four male, four female), mean age of 26.4+/-5.2 years, and BMI 22.3+/-2.6 kg/m(2), exposed to 9h of intermittent hypoxia between the hours of 10 P.M. and 7 A.M. for 28 consecutive nights. At a simulated altitude of 13,000 feet (FIO(2) 0.13), intermittent hypoxia was achieved by administering nasal nitrogen, alternating with brief (approximately 5s) boluses of nasal oxygen. Pre- and post-exposure assessments included polysomnography, attention (20-min Psychomotor Vigilance Test), working memory (10-min verbal 2 and 3-back), Multiple Sleep Latency Test, and the Rey Auditory Verbal Learning Test. Obstructive and non-obstructive respiratory events were scored. Overall sleep quality showed worsening trends but no statistically significant change following exposure. There was no difference after hypoxia in sleepiness, encoding, attention or working memory. Hyperoxic central apneas and post-hyperoxic respiratory instability were noted as special features of disturbed respiratory control induced by intermittent nocturnal hypoxia. In this model, exposure to nocturnal intermittent hypoxia for 4 weeks caused no significant deficits in subjective or objective alertness, vigilance, or working memory.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2008.00702.x

Journal of sleep research

J Sleep Res

Scheduled napping as a countermeasure to sleepiness in air traffic controllers.

The aims of this study were to measure sleep during a planned nap on the night shift; and to use objective measures of performance and alertness to compare the effects of the nap opportunity versus staying awake. Twenty-eight air traffic controllers (mean age 36 years, nine women) completed four night shifts (two with early starts and two with late starts). Each type of night shift (early/late start) included a 40-min planned nap opportunity on one occasion and no nap on the other. Polysomnographic data were used to measure sleep and waking alertness [spectral power in the electroencephalogram (EEG) during the last hour of the night shift and the occurrence of slow rolling eye movements (SEMs) subsequent to the nap]. Psychomotor performance task [Psychomotor Vigilance Task (PVT)] was completed at the beginning and end of the shift, and after the nap (or an equivalent time if no nap was taken). Nap sleep latencies were relatively long (mean = 19 min) and total sleep time short (mean = 18 min), with minimal slow wave sleep (SWS, mean = 0%), and no rapid eye movement sleep. Nap sleep resulted in improved PVT performance (mean and slowest 10% of reaction time events), decreased spectral power in the EEG and reduced the likelihood of SEMs. The occurrence of SWS in the nap decreased spectral power in the EEG. This study indicates that although sleep taken at work is likely to be short and of poor quality it still results in an improvement in objective measures of alertness and performance.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/32.2.205

Sleep

Sleep

Sustaining executive functions during sleep deprivation: A comparison of caffeine, dextroamphetamine, and modafinil.

Stimulant medications appear effective at restoring simple alertness and psychomotor vigilance in sleep deprived individuals, but it is not clear whether these medications are effective at restoring higher order complex cognitive capacities such as planning, sequencing, and decision making. After 44 hours awake, participants received a double-blind dose of one of 3 stimulant medications or placebo. After 45-50 hours awake, participants were tested on computerized versions of the 5-Ring Tower of Hanoi (TOH), the Tower of London (TOL), and the Wisconsin Card Sorting Test (WCST). In-residence sleep-laboratory facility at the Walter Reed Army Institute of Research. Fifty-four healthy adults (29 men, 25 women), ranging in age from 18 to 36 years. Participants were randomly assigned to 1 of 3 stimulant medication groups, including caffeine, 600 mg (n=12), modafinil, 400 mg (n=12), dextroamphetamine, 20 mg (n=16), or placebo (n=14). At the doses tested, modafinil and dextroamphetamine groups completed the TOL task in significantly fewer moves than the placebo group, and the modafinil group demonstrated greater deliberation before making moves. In contrast, subjects receiving caffeine completed the TOH in fewer moves than all 3 of the other groups, although speed of completion was not influenced by the stimulants. Finally, the modafinil group outperformed all other groups on indices of perseverative responding and perseverative errors from the WCST. Although comparisons across tasks cannot be made due to the different times of administration, within-task comparisons suggest that, at the doses tested here, each stimulant may produce differential advantages depending on the cognitive demands of the task.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/S0076-6879(08)03816-0

Methods in enzymology

Methods Enzymol

Modeling fatigue over sleep deprivation, circadian rhythm, and caffeine with a minimal performance inhibitor model.

Sleep loss, as well as concomitant fatigue and risk, is ubiquitous in today's fast-paced society. A biomathematical model that succeeds in describing performance during extended wakefulness would have practical utility in operational environments and could help elucidate the physiological basis of sleep loss effects. Eighteen subjects (14 males, 4 females; age 25.8 +/- 4.3 years) with low levels of habitual caffeine consumption (<300 mg/day) participated. On night 1, subjects slept for 8 h (2300-0700 h), followed by 77 h of continuous wakefulness. They were assigned randomly to receive placebo or caffeine (200 mg, i.e., two sticks of Stay Alert gum) at 0100, 0300, 0500, and 0700 during nights 2, 3, and 4. The psychomotor vigilance test (PVT) was administered periodically over the 77-h period of continuous wakefulness. Statistical analysis reveals lognormality in each PVT, allowing for closed-form median calculation. An iterative parameter estimation algorithm, which takes advantage of MatLab's (R2007a) least-squares nonlinear regression, is used to estimate model parameters from subjects' PVT medians over time awake. In the model, daily periodicity is accounted for with a four-component Fourier series, and a simplified binding function describes asymptotic fatigue. The model highlights patterns in data that suggest (1) the presence of a performance inhibitor that increases and saturates over the period of continuous wakefulness, (2) competitive inhibition of this inhibitor by caffeine, (3) the persistence of an internally driven circadian rhythm of alertness, and (4) a multiplicative relationship between circadian rhythm and performance inhibition. The present inhibitor-based minimal model describes performance data in a manner consistent with known biochemical processes.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.3357/asem.2396.2009

Aviation, space, and environmental medicine

Aviat Space Environ Med

Executive functions and the ability to sustain vigilance during sleep loss.

There is considerable individual variability in the ability to sustain performance during sleep loss. Preliminary evidence suggests that individuals with higher trait-like activation/functioning of the prefrontal cortex may be less vulnerable to fatigue. We tested this hypothesis in a sample of 54 healthy volunteers who were assessed bi-hourly on a variant of the Psychomotor Vigilance Test during 41 h of sleep deprivation. A subset of these subjects, representing the top and bottom 25% of the sample based on their ability to sustain vigilance performance during sleep deprivation, were compared with respect to baseline neurocognitive abilities. The sleep deprivation Resistant group (N = 13) scored significantly higher than the sleep deprivation Vulnerable (N = 13) group on all three baseline tasks assessing prefrontal executive function abilities (letter fluency, Stroop Color-Word test, Color Trails Form 2), whereas no differences were found on non-executive function tasks. Similarly, groups showed no differences on demographic variables including age, education, hand preference, morningness-eveningness preference, global intellectual ability, or pre-study sleep history. Findings are consistent with the hypothesis that greater prefrontal/executive functioning may be protective against the adverse effects of sleep deprivation and suggest that baseline executive function testing may prove useful for prediction of resilience during sleep loss.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.actaastro.2007.12.005

Acta astronautica

Acta Astronaut

Response Surface Mapping of Neurobehavioral Performance: Testing the Feasibility of Split Sleep Schedules for Space Operations.

The demands of sustaining high levels of neurobehavioral performance during space operations necessitate precise scheduling of sleep opportunities in order to best preserve optimal performance. We report here the results of the first split-sleep, dose-response experiment involving a range of sleep/wake scenarios with chronically reduced nocturnal sleep, augmented with a diurnal nap. To characterize performance over all combinations of split sleep in the range studied, we used response surface mapping methodology. Waking neurobehavioral performance was studied in N=90 subjects each assigned to one of 18 sleep regimens consisting of a restricted nocturnal anchor sleep period and a diurnal nap. Psychomotor vigilance task performance and subjective assessments of sleepiness were found to be primarily a function of total time in bed per 24 h regardless of how sleep was divided among nocturnal anchor sleep and diurnal nap periods. Digit symbol substitution task performance was also found to be primarily a function of total time in bed per 24 h; however, accounting for nocturnal sleep duration and nap duration separately provided a small but significant enhancement in the variance explained. The results suggest that reductions in total daily sleep result in a near-linear accumulation of impairment regardless of whether sleep is scheduled as a consolidated nocturnal sleep period or split into a nocturnal anchor sleep period and a diurnal nap. Thus, split sleep schedules are feasible and can be used to enhance the flexibility of sleep/work schedules for space operations involving restricted nocturnal sleep due to mission-critical task scheduling. These results are generally applicable to any continuous industrial operation that involves sleep restriction, night operations, and shift work.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.physbeh.2008.11.009

Physiology & behavior

Physiol Behav

Self-reported 'sleep deficit' is unrelated to daytime sleepiness.

Seemingly, many healthy adults have accrued a sleep debt, as determined by findings based on the multiple sleep latency test (MSLT). However, our recent, extensive survey found self-reported sleep deficit was not linked to daytime sleepiness determined by the Epworth sleepiness scale (ESS). Here, we report on the link between self-reported sleep deficit and gold standard measures of sleepiness: MSLT, Psychomotor vigilance test (PVT) and Karolinska Sleepiness Scale (KSS). Habitual sleep time in forty-three participants, from using a week long sleep diary and actiwatch data, compared with self-ratings of how much sleep they needed, provided estimates of apparent sleep deficit or otherwise. They were split into categories: 'sleep deficit' (Av. -47 min), 'sleep plus' (Av. 47 min) or 'neutral' (Av. 0+/-15 min), depicting perceived shortfall (or excess) sleep. Although the deficit group desired to sleep longer than the other groups, they actually obtained similar habitual nightly sleep as the neutral group, but less than the sleep plus group. 'Survival curves' based on those falling asleep during the MSLT showed no difference between the groups. Neither was there any difference between the groups for the PVT, KSS, or ESS. Here, factors other than sleepiness seem to influence self-perceived sleep deficits.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2008.00698.x

Journal of sleep research

J Sleep Res

24 hours of sleep deprivation in the rat increases sleepiness and decreases vigilance: introduction of the rat-psychomotor vigilance task.

A novel animal-analog of the human psychomotor vigilance task (PVT) was validated by subjecting rats to 24 h of sleep deprivation (SD) and examining the effect on performance in the rat-PVT (rPVT), and a rat multiple sleep latency test (rMSLT). During a three-phase (separate cohorts) crossover design, vigilance performance in the rPVT was compared with 24 h SD-induced changes in sleepiness assessed by polysomnographic evaluation and the rMSLT. Twenty-four hours of SD was produced by brief rotation of activity wheels at regular intervals in which the animals resided throughout the experiment. In the rPVT experiment, exercise controls (EC) experienced the same overall amount of locomotor activity as during SD, but allowed long periods of undisturbed sleep. After 24 h SD response latencies slowed, and lapses increased significantly during rPVT performance when compared with baseline and EC conditions. During the first 3 h of the recovery period following 24 h SD, polysomnographic measures indicated sleepiness. Latency to fall asleep after 24 h SD was assessed six times during the first 3 h after SD. Rats fell asleep significantly faster immediately after SD, than after non-SD baseline sessions. In conclusion, 24 h of SD in rats increased sleepiness, as indicated by polysomnography and the rMSLT, and impaired vigilance as measured by the rPVT. The rPVT closely resembles the human PVT test widely used in human sleep research and will assist investigation of the neurobiologic mechanisms that produce vigilance impairments after sleep disruption.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2008.00680.x

Journal of sleep research

J Sleep Res

Sleep extension versus nap or coffee, within the context of 'sleep debt'.

Though extended night-time sleep mostly reduces the 'afternoon dip', little is known about evening benefits to alertness, or about comparisons with an afternoon nap or caffeine. Twenty healthy carefully screened adults, normal waking alertness levels, underwent four counterbalanced conditions: usual night sleep; night sleep extended<90 min (usual bed-time); up to 20 min afternoon nap; and 150 mg afternoon caffeine (versus decaffeinated coffee). Sleepiness was measured by afternoon and evening multiple sleep latency test (MSLTs), longer psychomotor vigilance test (PVT) sessions and a subjective sleepiness scale. Sleep was extended by average of 74 min, and all participants could nap 15-20 min. Sleep extension had little effect on PVT determined modest levels of morning sleepiness. Afternoon and evening MSLTs showed all active treatments significantly reduced the 'dip', with nap most effective until mid-evening; next effective was caffeine, then extension. Late evening sleepiness and subsequent sleep did not differ between conditions. Arguably, participants may have experienced some 'sleep debt', given they extended sleep and reflected some sleepiness within settings sensitive to sleepiness. Nevertheless, extended sleep seemed largely superfluous and inefficient in reducing modest levels of sleepiness when compared with a timely nap, and even caffeine. Sleep, such as food and fluid intakes, can be taken to excess of real biological needs, and for many healthy adults, there is a level of modest daytime sleepiness, only unmasked by very sensitive laboratory measures. It may reflect a requirement for more sleep or simply be within the bounds of normal acceptability.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1080/07420520802551428

Chronobiology international

Chronobiol Int

Sleep loss and performance of anaesthesia trainees and specialists.

Fatigue risk associated with work schedules of hospital doctors is coming under increasing scrutiny, with much of the research and regulatory focus on trainees. However, provision of 24 h services involves both trainees and specialists, who have different but interdependent work patterns. This study examined work patterns, sleep (actigraphy, diaries) and performance (psychomotor vigilance task pre- and post-duty) of 28 anaesthesia trainees and 20 specialists across a two-week work cycle in two urban public hospitals. Trainees at one hospital worked back-to-back 12 h shifts, while the others usually worked 9 h day shifts but periodically worked a 14 h day (08:00-22:00 h) to maintain cover until arrival of the night shift (10 h). On 11% of day shifts and 23% of night shifts, trainees were working with> or =2 h of acute sleep loss. However, average sleep loss was not greater on night shifts, possibly because workload at night in one hospital often permitted some sleep. Post-night shift performance was worse than post-day shift performance for the median (t((131))=3.57, p<0.001) and slowest 10% of reaction times (t((134))=2.91, p<0.01). At the end of night shifts, poorer performance was associated with longer shift length, longer time since waking, greater acute sleep loss, and more total work in the past 24 h. Specialists at both hospitals had scheduled clinical duties during the day and were periodically scheduled on call to cover after-hours services. On 8% of day shifts and 14% of day+call schedules, specialists were working with> or =2 h of acute sleep loss. They averaged 0.6 h less sleep when working day shifts (t((23.5))=2.66, p=0.014) and 0.8 h less sleep when working day shifts+call schedules (t((26.3))=2.65, p=0.013) than on days off. Post-duty reaction times slowed linearly across consecutive duty days (median reaction time, t((131))=-3.38, p<0.001; slowest 10%, t((160))=-3.33, p<0.01; fastest 10%, t((138))=-2.67, p<0.01). Poorer post-duty performance was associated with greater acute sleep loss and longer time since waking, but better performance was associated with longer day shifts, consistent with circadian improvement in psychomotor performance across the waking day. This appears to be the first study to document sleep loss among specialist anaesthetists. Consistent with observations from experimental studies, the sleep loss of specialists across 12 consecutive working days was associated with a progressive decline in post-duty PVT performance. However, this decline occurred with much less sleep restriction (< 1 h per day) than in laboratory studies, suggesting an exacerbating effect of extended wakefulness and/or cumulative fatigue associated with work demands. For both trainees and specialists, robust circadian variation in PVT performance was evident in this complex work setting, despite the potential confounds of variable shift durations and workloads. The relationship between PVT performance of an individual and the safe administration of anaesthesia in the operating theater is unknown. Nevertheless, the findings reinforce that any schedule changes to reduce work-related fatigue need to consider circadian performance variation and the potential transfer of workload and fatigue risk between trainees and specialists.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.3758/BRM.40.4.1016

Behavior research methods

Behav Res Methods

The driver vigilance telemetric control system (DVTCS): investigating sensitivity to experimentally induced sleep loss and fatigue.

Vigilance technologies are used in the Australian rail industry to address the risks associated with driver sleepiness and fatigue. The aim of this study was to investigate whether a new device, designed to detect lowered states of arousal using electrodermal activity (EDA), would be sensitive to experimentally induced sleepiness and fatigue. Fifteen individuals (7 of them female, 9 male; 18-32 years of age) spent 3 consecutive days in the laboratory, which included 1 night of sustained wakefulness (28 h). The participants completed a 10-min psychomotor vigilance task (PVT) and fatigue and sleepiness ratings every 2 h, and a 30-min driving simulator every 4 h. As was expected, simulated driving, PVT, and subjective ratings indicated increasing levels of sleepiness and fatigue during sustained wakefulness. The EDA device output did not coincide with these findings. The results indicated that the EDA indicator was not sensitive to increased sleepiness and fatigue at the levels produced in the present study.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.jtbi.2008.09.012

Journal of theoretical biology

J Theor Biol

A new mathematical model for the homeostatic effects of sleep loss on neurobehavioral performance.

The two-process model of sleep regulation makes accurate predictions of sleep timing and duration for a variety of experimental sleep deprivation and nap sleep scenarios. Upon extending its application to waking neurobehavioral performance, however, the model fails to predict the effects of chronic sleep restriction. Here we show that the two-process model belongs to a broader class of models formulated in terms of coupled non-homogeneous first-order ordinary differential equations, which have a dynamic repertoire capturing waking neurobehavioral functions across a wide range of wake/sleep schedules. We examine a specific case of this new model class, and demonstrate the existence of a bifurcation: for daily amounts of wakefulness less than a critical threshold, neurobehavioral performance is predicted to converge to an asymptotically stable state of equilibrium; whereas for daily wakefulness extended beyond the critical threshold, neurobehavioral performance is predicted to diverge from an unstable state of equilibrium. Comparison of model simulations to laboratory observations of lapses of attention on a psychomotor vigilance test (PVT), in experiments on the effects of chronic sleep restriction and acute total sleep deprivation, suggests that this bifurcation is an essential feature of performance impairment due to sleep loss. We present three new predictions that may be experimentally verified to validate the model. These predictions, if confirmed, challenge conventional notions about the effects of sleep and sleep loss on neurobehavioral performance. The new model class implicates a biological system analogous to two connected compartments containing interacting compounds with time-varying concentrations as being a key mechanism for the regulation of psychomotor vigilance as a function of sleep loss. We suggest that the adenosinergic neuromodulator/receptor system may provide the underlying neurobiology.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Sleep

Sleep

Microdialysis elevation of adenosine in the basal forebrain produces vigilance impairments in the rat psychomotor vigilance task.

The inhibitory neuromodulator adenosine has been proposed as a homeostatic sleep factor that acts potently in the basal forebrain (BF) to increase sleepiness. Here 300 microM of adenosine was dialyzed in the BF of rats, and the effect on vigilance was determined in the rat Psychomotor Vigilance Task (rPVT). Rats experienced all experimental conditions in a repeated-measures, cross-over design. Twelve young adult male Fischer-Norway rats. Sustained attention performance in the rPVT was evaluated following 2 hours of bilateral microdialysis perfusion of vehicle, adenosine (300 microM), or codialysis of 300 microM of adenosine with the A1 receptor antagonist 8-cyclopentyltheophylline. During rPVT performance, response latencies and performance lapses increased significantly after adenosine dialysis when compared with baseline (no dialysis) or vehicle dialysis sessions. The codialysis of 8-cyclopentyltheophylline with adenosine completely blocked the effects produced by adenosine alone, resulting in performance equivalent to that of the vehicle sessions. Pharmacologic elevation of BF adenosine in rats produced vigilance impairments resembling the effect of sleep deprivation on vigilance performance in both man and rats. This effect of exogenous adenosine was completely blocked by codialysis with an adenosine A1 receptor antagonist. The results are consistent with the hypothesis that sleep loss induces elevations of BF adenosine that, acting via A1 receptors, lead to increased sleepiness and impaired vigilance.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1590/s0100-879x2008000800016

Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas

Braz J Med Biol Res

Influence of gender on psychomotor vigilance task performance by adolescents.

During adolescence, the sleep phase delay associated with early school times increases daytime sleepiness and reduces psychomotor performance. Some studies have shown an effect of gender on psychomotor performance in adults and children. Males present faster reaction times (RT) compared with females. The aim of the present study was to evaluate the influence of gender on Palm psychomotor vigilance task (PVT) performance in adolescents. Thirty-four adolescents (19 girls, 13 to 16 years old) attending morning school classes of a public school in Curitiba, PR, Brazil, participated in the study. Sleep patterns were measured using actigraphy and sleepiness data were accessed with the Karolinska Sleepiness Scale (KSS). KSS and PVT measurements were collected at two times in the morning (8:00 and 11:00 h). The data were compared using one-way ANOVA, considering gender as a factor. ANOVA indicated that gender did not affect sleep patterns and subjective somnolence; however, a statistically significant effect of gender was detected for PVT performance. Boys presented faster RT (RT-PVT1: 345.51 ms, F = 6.08, P < 0.05; RT-PVT2: 343.30 ms, F = 6.35, P < 0.05) and fewer lapses (lapses-PVT1: 8.71, F = 4.45, P < 0.05; lapses-PVT2: 7.82, F = 7.06, P < 0.05) compared with girls (RT-PVT1: 402.96; RT-PVT2: 415.70; lapses-PVT1: 16.33; lapses-PVT2: 17.80). These results showed that this effect of gender, already reported in adults and children, is also observed in adolescents. The influence of gender should be taken into account in studies that use Palm PVT to evaluate psychomotor performance in this age range.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1440-1843.2008.01392.x

Respirology (Carlton, Vic.)

Respirology

Acute oxygen therapy does not improve cognitive and driving performance in hypoxaemic COPD.

Cognitive and neuropsychological function may be adversely affected by low blood oxygen levels and this has been previously demonstrated in hypoxaemic COPD. The aim of this study was to assess whether supplemental oxygen therapy while driving a motor vehicle is justified in hypoxaemic COPD. We therefore used computer-based driving simulation to investigate whether acute intranasal oxygen therapy improves the cognitive and driving performance of such patients. Thirty hypoxaemic COPD subjects with a current driving licence performed a 20-min computer-based driving simulation task and a 10-min psychomotor vigilance task (PVT) at baseline, and while breathing intranasal oxygen or intranasal air in a randomized, double-blind, cross-over protocol. The mean (SD) age of the subjects was 72 years (8) and their mean driving experience was 50 years (10). Mean FEV(1) was 41% (18) of predicted and PaO(2) was 50.5 mm Hg (4.7) on air and 70.7 mm Hg (9.1) on oxygen. There were no statistically significant differences in any measure of driving performance or in reaction time measurements while breathing oxygen compared with air. Acute oxygen therapy does not improve simulated driving performance or neurocognitive function as assessed by PVT in patients with hypoxaemic COPD. These data do not support the recommendation that oxygen should be used by this patient group while driving.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1080/00207450801941368

The International journal of neuroscience

Int J Neurosci

Baseline odor identification ability predicts degradation of psychomotor vigilance during 77 hours of sleep deprivation.

Scores on the University of Pennsylvania Smell Identification Test, a measure of the functional integrity of the orbitofrontal cortex, were used to predict the vulnerability to cognitive declines during 77 hr of sleep deprivation. Twenty-one healthy volunteers completed the Smell Identification Test at rested baseline followed by repeated psychomotor vigilance testing throughout each night. Participants with better smell identification abilities sustained faster speeds and fewer lapses on the second and third nights of sleep deprivation than participants with lower scores. Individual differences in trait-like functioning of the orbitofrontal cortex are predictive of the ability to sustain alertness and vigilance during continuous wakefulness.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.apergo.2008.06.003

Applied ergonomics

Appl Ergon

A field study of sleep and fatigue in a regular rotating 12-h shift system.

The aim of this study was to examine a regular rotating 12-h shift system (2D2N4Off) at an Australian Smelter. Sleep behavior, subjective fatigue and neurobehavioral performance were investigated over a 14-day period for 20 employees. Activity monitors, sleep/wake diaries, and 5-min psychomotor vigilance tasks were used. Sleep data showed differences between day and night shifts. While sleep prior to night1 was increased relative to day shifts, a reduced sleep length carried into the period leading to night2. Total wakefulness at the end of shift, and subjective fatigue were increased for night shifts, particularly night1. Decrements in performance data supported these findings. Both prior wakefulness and prior sleep are important in a 12-h shift system. Employees may "sleep in" after day shifts, rather than taking extra sleep prior to night work. Thus, sleep between day and night shifts is based on recovery rather than preparation.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1177/0748730408319863

Journal of biological rhythms

J Biol Rhythms

The impact of sleep timing and bright light exposure on attentional impairment during night work.

The prevalence of hazardous incidents induced by attentional impairment during night work and ensuing commute times is attributable to circadian misalignment and increased sleep pressure. In a 10-day shift work simulation protocol (4 day shifts and 3 night shifts), the efficacies of 2 countermeasures against nighttime (2300 to 0700 h) attentional impairment were compared: (1) Morning Sleep (0800 to 1600 h; n = 18) in conjunction with a phase-delaying light exposure (2300 to 0300 h), and (2) Evening Sleep (1400 to 2200 h; n = 17) in conjunction with a phase-advancing light exposure (0300 to 0700 h). Analysis of the dim light salivary melatonin onset indicated a modest but significant circadian realignment in both sleep groups (evening sleep: 2.27 +/- 0.6 h phase advance, p < 0.01; morning sleep: 4.98 +/- 0.43 h phase delay, p < 0.01). Daytime sleep efficiency and total sleep time did not differ between them or from their respective baseline sleep (2200 to 0600 h; p > 0.05). However, on the final night shift, the evening sleep subjects had 37% fewer episodes of attentional impairment (long response times: 22 +/- 4 vs. 35 +/- 4; p = 0.02) and quicker responses (p < 0.01) on the Psychomotor Vigilance Task than their morning sleep counterparts. Their response speed recovered to near daytime levels (p = 0.47), whereas those of the morning sleep subjects continued to be slower than their daytime levels (p = 0.008). It is concluded that partial circadian realignment to night work in combination with reduced homeostatic pressure contributed to the greater efficacy of a schedule of Evening Sleep with a phase-advancing light exposure as a countermeasure against attentional impairment, over a schedule of Morning Sleep with a phase-delaying light exposure. These results have important implications for managing patients with shift work disorder.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.otohns.2008.03.012

Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery

Otolaryngol Head Neck Surg

Randomized placebo-controlled trial of pantoprazole for daytime sleepiness in GERD and obstructive sleep disordered breathing.

To determine the efficacy of pantoprazole therapy for daytime somnolence, psychomotor vigilance, and quality of life in patients with mild-moderate obstructive sleep disordered breathing (OSDB) and gastroesophageal reflux disease (GERD). Randomized, double-blind, placebo-controlled crossover trial. Sixty patients with daytime sleepiness, mild-moderate OSDB and GERD were randomly assigned a 2-week treatment with pantoprazole 40 mg or placebo followed by a 2-week washout period and crossover respectively to 2-week treatment with placebo or pantoprazole. Outcomes included Epworth Sleepiness Score (ESS), sleep-related quality-of-life (FOSQ), and reaction time. With pantoprazole, patients reported statistically significantly greater improvement of overall reflux symptoms (P = 0.0003) and in ESS (P = 0.04). A significant improvement was noted in FOSQ for both treatments with a trend toward greater improvement with pantoprazole (P = 0.058). No improvement in reaction times was observed. Patients with coexistent GERD and OSDB noted significant improvement in daytime sleepiness after treatment with pantoprazole over placebo likely related to a reduction in nocturnal reflux-related arousals.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1088/0967-3334/29/8/001

Physiological measurement

Physiol Meas

Combined electrocardiogram and photoplethysmogram measurements as an indicator of objective sleepiness.

There is considerable interest in unobtrusive and portable methods of monitoring sleepiness outside the laboratory setting. This study evaluates the usefulness of combined electrocardiogram (ECG) and photoplethysmogram (PPG) measurements for estimating psychomotor vigilance. The psychomotor vigilance test (PVT) was performed at various points over the course of a day, and one channel each of ECG and PPG was recorded simultaneously. Features derived from ECG and PPG were entered into multiple linear regression models to estimate PVT values. A double-loop, subject-independent validation scheme was used to develop and validate the models. We show that features obtained from the RR interval were reasonably useful for estimating absolute PVT levels, but were somewhat inadequate for estimating within-subject PVT changes. Combined ECG and PPG measurements appear to be useful for predicting PVT values, and deserve further investigation for portable sleepiness monitoring.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1196/annals.1417.002

Annals of the New York Academy of Sciences

Ann N Y Acad Sci

Sleep deprivation and vigilant attention.

Sleep deprivation severely compromises the ability of human beings to respond to stimuli in a timely fashion. These deficits have been attributed in large part to failures of vigilant attention, which many theorists believe forms the bedrock of the other more complex components of cognition. One of the leading paradigms used as an assay of vigilant attention is the psychomotor vigilance test (PVT), a high signal-load reaction-time test that is extremely sensitive to sleep deprivation. Over the last twenty years, four dominant findings have emerged from the use of this paradigm. First, sleep deprivation results in an overall slowing of responses. Second, sleep deprivation increases the propensity of individuals to lapse for lengthy periods (>500 ms), as well as make errors of commission. Third, sleep deprivation enhances the time-on-task effect within each test bout. Finally, PVT results during extended periods of wakefulness reveal the presence of interacting circadian and homeostatic sleep drives. A theme that links these findings is the interplay of "top-down" and "bottom-up" attention in producing the unstable and unpredictable patterns of behavior that are the hallmark of the sleep-deprived state.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2008.00654.x

Journal of sleep research

J Sleep Res

Effects of dextroamphetamine, caffeine and modafinil on psychomotor vigilance test performance after 44 h of continuous wakefulness.

Prolonged sleep loss impairs alertness, vigilance and some higher-order cognitive and affective capacities. Some deficits can be temporarily reversed by stimulant medications including caffeine, dextroamphetamine, and modafinil. To date, only one study has directly compared the effectiveness of these three compounds and specified the doses at which all were equally effective in restoring alertness and vigilance following 64 h of wakefulness. The present study compared the effectiveness of these same three stimulants/doses following a less extreme period of sleep loss (i.e., 44 h). Fifty-three healthy adults received a single dose of modafinil 400 mg (n = 11), dextroamphetamine 20 mg (n = 16), caffeine 600 mg (n = 12), or placebo (n = 14) after 44 h of continuous wakefulness. After 61 h of being awake, participants obtained 12 h of recovery sleep. Psychomotor vigilance was assessed bi-hourly during waking and following recovery sleep. Relative to placebo, all three stimulants were equally effective in restoring psychomotor vigilance test speed and reducing lapses, although the duration of action was shortest for caffeine and longest for dextroamphetamine. At these doses, caffeine was associated with the highest percentage of subjectively reported side-effects while modafinil did not differ significantly from placebo. Subsequent recovery sleep was adversely affected in the dextroamphetamine group, but none of the stimulants had deleterious effects on postrecovery performance. Decisions regarding stimulant selection should be made with consideration of how factors such as duration of action, potential side-effects, and subsequent disruption of recovery sleep may interact with the demands of a particular operational environment.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2008.00665.x

Journal of sleep research

J Sleep Res

Comparing the neurocognitive effects of 40 h sustained wakefulness in patients with untreated OSA and healthy controls.

We hypothesized that individuals with untreated obstructive sleep apnea (OSA) would exhibit greater vulnerability to sleep deprivation than healthy controls, due to the additional neurobiological 'load' of chronic sleep fragmentation. After baseline sleep with 8 h time in bed, participants remained awake for 40 h. Psychomotor Vigilance Task (PVT, mean slowest 10% 1/RT), AusEd Driving Simulator task (steering and speed deviation), and subjective sleepiness (Karolinska Sleepiness Scale, KSS) were assessed every 2 h. Nonlinear mixed-effects models were used to characterize individual differences in baseline/average performance, the linear effect of increasing hours awake, circadian amplitude and phase. Eight participants with untreated OSA with mean (SD) age 44.6 (8.4), apnea-hypopnea index (AHI) 49.8 (24.7), Epworth Sleepiness Scale (ESS) 11.9 (4.8) and nine healthy controls age 27.8 (3.7), AHI 4.5 (2.7), ESS 7.3 (2.1) completed the protocol. Baseline KSS was significantly higher (1.4 units, P = 0.03) in the OSA group and there was a trend toward lower baseline speed deviation on the AusEd (P = 0.05). After adjusting for the significant effects of accumulated time awake, circadian amplitude and phase (all P < 0.005), there was no difference in performance decrements between those with and without sleep apnea in PVT, driving simulator performance and subjective sleepiness (P > 0.5). Random-effects modeling confirmed the presence of significant inter-individual variability in vulnerability to sleep deprivation. Patients with OSA did not respond differently to sleep deprivation than healthy controls. As expected, total sleep deprivation led to significant worsening in performance and subjective sleepiness in both groups.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/31.5.659

Sleep

Sleep

Slow wave sleep enhancement with gaboxadol reduces daytime sleepiness during sleep restriction.

To evaluate the impact of enhanced slow wave sleep (SWS) on behavioral, psychological, and physiological changes resulting from sleep restriction. A double-blind, parallel group, placebo-controlled design was used to compare gaboxadol (GBX) 15 mg, a SWS-enhancing drug, to placebo during 4 nights of sleep restriction (5 h/night). Behavioral, psychological, and physiological measures of the impact of sleep restriction were assessed in both groups at baseline, during sleep restriction and following recovery sleep. Sleep research laboratory. Forty-one healthy adults; 9 males and 12 females (mean age: 32.0 +/- 9.9 y) in the placebo group and 10 males and 10 females (mean age: 31.9 +/- 10.2 y) in the GBX group. Both experimental groups underwent 4 nights of sleep restriction. Each group received either GBX 15 mg or placebo on all sleep restriction nights, and both groups received placebo on baseline and recovery nights. Polysomnography documented a SWS-enhancing effect of GBX with no group difference in total sleep time during sleep restriction. The placebo group displayed the predicted deficits due to sleep restriction on the multiple sleep latency test (MSLT) and on introspective measures of sleepiness and fatigue. Compared to placebo, the GBX group showed significantly less physiological sleepiness on the MSLT and lower levels of introspective sleepiness and fatigue during sleep restriction. There were no differences between groups on the psychomotor vigilance task (PVT) and a cognitive test battery, but these measures were minimally affected by sleep restriction in this study. The correlation between change from baseline in MSLT on Day 6 and change from baseline in SWS on Night 6 was significant in the GBX group and in both group combined. The results of this study are consistent with the hypothesis that enhanced SWS, in this study produced by GBX, reduces physiological sleep tendency and introspective sleepiness and fatigue which typically result from sleep restriction.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1007/s11325-008-0189-3

Sleep & breathing = Schlaf & Atmung

Sleep Breath

Randomised trial of compliance with flexible (C-Flex) and standard continuous positive airway pressure for severe obstructive sleep apnea.

Obstructive sleep apnea (OSA) is often treated with continuous positive airway pressure (CPAP) but the effectiveness of treatment is probably limited by poor compliance. CPAP manufacturers are thus attempting to devise more comfortable PAP devices in an effort to improve compliance. An example of such a novel device is Flexible expiratory-modulated PAP (C-Flex mode Respironics REMstar Pro, Murraysville, PA, USA). We aimed to compare compliance between C-Flex and standard CPAP in patients with severe OSA in a randomised controlled trial. Nineteen patients with severe OSA (mean +/- SD Apnea Hypopnea Index = 78 +/- 33/h, Epworth 14 +/- 4, PAP 8-17 cm H2O, BMI = 39 +/- 10 kg/m2) and aged 20-63 years were randomly assigned to 4 weeks of either C-Flex (setting II, n = 9) or CPAP (n = 10). Patients treated with C-Flex exhibited a trend toward higher compliance with their PAP devices compared to patients treated with standard CPAP (4.7 +/- 2.9 vs. 3.0 +/- 2.1 h/night, p = 0.15, effect size = 0.68). Paradoxically, improvements in subjective sleepiness (Epworth Sleepiness Scale) were greater in those who received CPAP than C-Flex (8.1 + 4.9 vs. 2.1 + 4.0 points, p = 0.014, effect size = 1.46). Improvements in objective wakefulness (Modified Maintenance of Wakefulness Test) and simple reaction times (Psychomotor Vigilance Task) were not significantly different between treatments. This randomised trial provides some evidence that C-Flex might increase initial treatment compliance, compared to CPAP, in patients with severe OSA. However, this trend toward greater compliance was not associated with better short-term treatment outcomes for patients. These findings need to be confirmed in a larger, longer-term trial.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.3758/brm.40.1.347

Behavior research methods

Behav Res Methods

The sensitivity of a palm-based psychomotor vigilance task to severe sleep loss.

In this study, we evaluated the sensitivity of a 5-min personal digital assistant-psychomotor vigilance test (PDA-PVT) to severe sleep loss. Twenty-one participants completed a 10-min PVT-192 and a 5-min PDA-PVT at two hourly intervals during 62 h of sustained wakefulness. For both tasks, response speed and number of lapses (RTs > 500) per minute significantly increased with increasing hours of wakefulness. Overall, standardized response speed scores on the 5-min PDA-PVT closely tracked those of the PVT-192; however, the PDA-PVT was generally associated with more lapses/minute. Closer inspection of the data indicated that when the level of sleep loss and fatigue became more severe (i.e., Day 3), the 5-min PDA-PVT was not quite as sensitive as the 10-min PVT-192 when 2- to 10-sec foreperiods were used for both. It is likely, however, that the observed differences between the two devices was due to differences in task length. Thus, the findings provide further evidence of the validity of the 5-min PDA-PVT as a substitute for the 10-min PVT-192, particularly in circumstances in which a shorter test is required and/or the PVT-192 is not as practical.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.clinph.2007.12.021

Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology

Clin Neurophysiol

Long-term deficits of preterm birth: evidence for arousal and attentional disturbances.

Quantitative measures of pre-attentional, attentional and frontal lobe processes were compared to evaluate quantitative measures of these deficits in Ex-Preterm vs. Ex-Term adolescents. We compared 43 Ex-Preterm with 26 Ex-Term adolescents using the P50 auditory potential, the Psychomotor Vigilance Task (PVT), a reaction time (RT) test, and Near Infrared Spectroscopy (NIRS). The mean amplitude (+/-SE) of the P50 amplitude was similar in the Ex-Preterm (1.8+/-1.4 microV) vs. Ex-Term adolescents (1.8+/-0.6 microV, df = 68, F = 0.05, p = 0.8), but the Ex-Preterm group showed a trimodal distribution in amplitude (High, 3.3+/-0.4 microV, df=42.25, F=19.2, p < 0.01; Medium, 1.7+/-0.1 microV, df = 39, F = 0.41, p = 0.53; Low, 0.7+/-0.1 microV, df = 40, F = 49.5, p < 0.01) suggested by statistically significant variance between populations (Kolmogorov-Kuiper test, df = 42.25, F = 5.4, p < 0.01). Mean RT was longer in Ex-Preterm (250+/-8 ms) vs. Ex-Term subjects (200+/-5 ms, df = 68, F = 18.8, p < 0.001). PVT lapses were increased in Ex-Preterm subjects, and varied inversely with P50 amplitude (Overall Mean 17+/-5 lapses, df = 67, F = 5.34, p < 0.05; Low P50 amplitude, 25+/-10, df = 40, F = 8.8, p < 0.01; Medium, 21+/-11, df = 38, F = 5.37, p < 0.05; High, 6+/-2, df = 39, F = 6.78, p < 0.01) vs. Ex-Term subjects (2+/-0.4 lapses, p < 0.01). NIRS levels did not differ statistically, but tended to correlate with P50 amplitude in the Ex-Preterm group. These findings suggest differential pre-attentional, attentional and frontal lobe dysfunction in Ex-Preterm adolescents. These measures could provide a means to objectively assess differential dysregulation of arousal and attention in Ex-Preterm adolescents, allowing optimization of therapeutic designs.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.bbr.2008.02.007

Behavioural brain research

Behav Brain Res

Daytime vigilance in chronotypes: diurnal variations and effects of behavioral sleep fragmentation.

Vigilance levels of 12 morning types (M-types) and 12 evening types (E-types) were investigated after a baseline night, 2 nights of sleep fragmentation (5 min of forced awakening every half-hour) and a recovery night. Sleep timing was adjusted to the preferred sleep schedule of each subject. Daytime vigilance levels were assessed with test series including a scale of subjective alertness, a psychomotor vigilance task (PVT), a waking EEG recording, and a sleep latency test. Test series were administered every 4h, beginning 1.5h after wake time. On the baseline day, significant diurnal variations were found for each vigilance measure, except for the PVT. Diurnal variations were similar in M-types and E-types. Sleep fragmentation decreased vigilance levels on each measure, except the PVT. Effects of sleep fragmentation and recovery were similar in the two chronotypes. These results highlight the similarities in diurnal variations of vigilance in the two chronotypes when studied at their preferred sleep schedule. Results were also compared between chronotypes with extremely early or late circadian phases ("Extreme" subgroup) and between those with similar, intermediate circadian phases ("Intermediate" subgroup). Diurnal variations of subjective alertness and sleep latencies differed between "Extreme" chronotypes but were identical between "Intermediate" chronotypes. There were no major differences in the response to sleep fragmentation in any subgroup. Since phase angles differed by the same amount between chronotypes within each subgroup, the results suggest that a difference in phase angle cannot be the only source of the differences observed in diurnal variations between "Extreme" chronotypes.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1002/hup.931

Human psychopharmacology

Hum Psychopharmacol

Placebo response to caffeine improves reaction time performance in sleepy people.

Caffeine is the most widely used stimulant to counteract sleepiness. However, little is known about any placebo effect of caffeine in sleepy people and the effect of suggestibility. Over a 95 min test period, and in a counterbalanced design, 16 young healthy adults underwent 3 x 30 min sessions at the psychomotor vigilance test (PVT), during an early afternoon 'dip' enhanced by a prior night's sleep restriction (5 h). On both occasions they were given a cup of a decaffeinated coffee; once when the participant was verbally primed to suggest the coffee was caffeinated (Placebo) and on the other under neutral priming (Control). There were significantly fewer lapses and shorter reaction times following Placebo, for the initial two 30 min sessions, indicating that suggestion about consuming caffeine was effective in improving performance in moderately sleepy people.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1080/10284150701722273

Nutritional neuroscience

Nutr Neurosci

Cognitive methods for assessing mental energy.

Mental energy is not well defined but of considerable public interest. Although the physical energy required to complete a task can be objectively specified, the concept of mental energy is relatively new. Mental energy is a mood, but can also be defined as ability or willingness to engage in cognitive work. This review addresses the concept of mental energy and cognitive tests used to assess it. Methods that can be used to assess mental energy, including tests of cognitive performance, mood questionnaires, electrophysiological techniques, brain scanning technologies, and ambulatory monitoring, are discussed. Studies of the factors affecting mental energy, such as drugs, foods, sleep deprivation, and disease states, are also reviewed. In aggregate, the studies reviewed suggest use of cognitive tests that assess vigilance, ability to sustain attention, and choice reaction time are optimal for assessment of mental energy. Specific tests recommended include the psychomotor vigilance task, Wilkinson four-choice visual reaction time, the scanning visual vigilance test, and Wilkinson auditory vigilance test. These tests are sensitive to factors that both increase and decrease mental energy. Critical factors in the design and conduct of studies used to assess mental energy are also discussed.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2008.00635.x

Journal of sleep research

J Sleep Res

Relationships between affect, vigilance, and sleepiness following sleep deprivation.

This pilot study examined the relationships between the effects of sleep deprivation on subjective and objective measures of sleepiness and affect, and psychomotor vigilance performance. Following an adaptation night in the laboratory, healthy young adults were randomly assigned to either a night of total sleep deprivation (SD group; n = 15) or to a night of normal sleep (non-SD group; n = 14) under controlled laboratory conditions. The following day, subjective reports of mood and sleepiness, objective sleepiness (Multiple Sleep Latency Test and spontaneous oscillations in pupil diameter, PUI), affective reactivity/regulation (pupil dilation responses to emotional pictures), and psychomotor vigilance performance (PVT) were measured. Sleep deprivation had a significant impact on all three domains (affect, sleepiness, and vigilance), with significant group differences for eight of the nine outcome measures. Exploratory factor analyses performed across the entire sample and within the SD group alone revealed that the outcomes clustered on three orthogonal dimensions reflecting the method of measurement: physiological measures of sleepiness and affective reactivity/regulation, subjective measures of sleepiness and mood, and vigilance performance. Sleepiness and affective responses to sleep deprivation were associated (although separately for objective and subjective measures). PVT performance was also independent of the sleepiness and affect outcomes. These findings suggest that objective and subjective measures represent distinct entities that should not be assumed to be equivalent. By including affective outcomes in experimental sleep deprivation research, the impact of sleep loss on affective function and their relationship to other neurobehavioral domains can be assessed.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2008.00629.x

Journal of sleep research

J Sleep Res

Sharp and sleepy: evidence for dissociation between sleep pressure and nocturnal performance.

While sleep restriction decreases performance, not all individuals are equal with regard to sensitivity to sleep loss. We tested the hypothesis that performance could be independent of sleep pressure as defined by EEG alpha-theta power. Twenty healthy subjects (10 vulnerable and 10 resistant) underwent sleep deprivation for 25 h. Subjects had to rate their sleepiness (Karolinska Sleepiness Scale) and to perform a 10-min psychomotor vigilance task (PVT) every 2 h (20:00-08:00 hours). Sleep pressure was measured by EEG power spectral analysis (alpha-theta band 6.0-9.0 Hz). Initial performance, EEG spectral power and KSS score were equal in both groups (ANOVA, NS). The performance of vulnerable subjects significantly increased during the night (rANOVA, P < 0.01), whereas resistant subjects globally sustained their performance. Homeostatic pressure and subjective sleepiness significantly increased during the night (rANOVA, P < 0.01) identically in both categories (rANOVA, NS). Resistant subjects sustained their reaction time independently of the increase in homeostatic pressure. The phenotypic determinants of vulnerability to extended wakefulness remain unknown.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/31.2.233

Sleep

Sleep

Manipulation of core body and skin temperature improves vigilance and maintenance of wakefulness in narcolepsy.

Impaired vigilance and sleepiness are two majordaily complaints of patients with narcolepsy. We previously showed their sleepiness to be correlated to an abnormally regulated skin temperature, i.e., increased distal skin temperature compared with proximal skin temperature. Our goal was to investigate a possible causal contribution of skin temperature disturbances to impairments in the ability to maintain vigilance and wakefulness in narcolepsy. In a modified constant routine protocol, the Psychomotor Vigilance Task (PVT) and the Maintenance of Wakefulness Test (MWT) were repeatedly assessed. Meanwhile, skin and core body temperatures were mildly manipulated within the thermoneutral range of the normal diurnal rhythm using a thermosuit and hot or cold food and drinks. Tertiary narcolepsy referral center in a university hospital Eight patients (5 males) diagnosed with narcolepsy with cataplexy according to the ICSD-2 criteria (mean age +/- SD: 28.6 +/- 6.4, range 18-35 years). None. MWT sleep latency and PVT response speed. Compared to core cooling, core warming attenuated the typical decline in PVT response speed with increasing time-on-task by 25% (P = 0.02). Compared to distal skin warming, distal skin cooling increased the time that the patients were able to maintain wakefulness by 24% (distal warming: 1.88 min. vs. distal warming: 2.34 min.; P < 0.01). Core body and skin temperatures causally affect vigilance and sleepiness in narcolepsy. This could lead to future practical applications.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.aap.2007.07.008

Accident; analysis and prevention

Accid Anal Prev

Chasing the silver bullet: measuring driver fatigue using simple and complex tasks.

Driver fatigue remains a significant cause of motor-vehicle accidents worldwide. New technologies are increasingly utilised to improve road safety, but there are no effective on-road measures for fatigue. While simulated driving tasks are sensitive, and simple performance tasks have been used in industrial fatigue management systems (FMS) to quantify risk, little is known about the relationship between such measures. Establishing a simple, on-road measure of fatigue, as a fitness-to-drive tool, is an important issue for road safety and accident prevention, particularly as many fatigue related accidents are preventable. This study aimed to measure fatigue-related performance decrements using a simple task (reaction time - RT) and a complex task (driving simulation), and to determine the potential for a link between such measures, thus improving FMS success. Fifteen volunteer participants (7 m, 8 f) aged 22-56 years (mean 33.6 years), underwent 26 h of supervised wakefulness before an 8h recovery sleep opportunity. Participants were tested using a 30-min interactive driving simulation test, bracketed by a 10-min psychomotor vigilance task (PVT) at 4, 8, 18 and 24h of wakefulness, and following recovery sleep. Extended wakefulness caused significant decrements in PVT and driving performance. Although these measures are clearly linked, our analyses suggest that driving simulation cannot be replaced by a simple PVT. Further research is needed to closely examine links between performance measures, and to facilitate accurate management of fitness to drive, which requires more complex assessments of performance than RT alone.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1136/thx.2007.081315

Thorax

Thorax

Randomised trial of CPAP vs bilevel support in the treatment of obesity hypoventilation syndrome without severe nocturnal desaturation.

Untreated, obesity hypoventilation is associated with significant use of health care resources and high mortality. It remains unclear whether continuous positive airway pressure (CPAP) or bilevel ventilatory support (BVS) should be used as initial management. The aim of this study was to determine if one form of positive pressure is superior to the other in improving daytime respiratory failure. A prospective randomised study was performed in patients with obesity hypoventilation referred with respiratory failure. After exclusion of patients with persisting severe nocturnal hypoxaemia (Spo(2) < 80% for > 10 min) or carbon dioxide retention (> 10 mm Hg) despite optimal CPAP, the remaining patients were randomly assigned to receive either CPAP or BVS over a 3-month period. The primary outcome was change in daytime carbon dioxide level. Secondary outcome measures included daytime sleepiness, quality of life, compliance with treatment and psychomotor vigilance testing. Thirty-six patients were randomised to either home CPAP (n = 18) or BVS (n = 18). The two groups did not differ significantly at baseline with regard to physiological or clinical characteristics. Following 3 months of treatment, daytime carbon dioxide levels decreased in both groups (CPAP 6 (8) mm Hg; BVS 7 (7) mm Hg) with no between-group differences. There was no difference in compliance between the two treatment groups (5.8 (2.4) h/night CPAP vs 6.1 (2.1) h/night BVS). Although both groups reported an improvement in daytime sleepiness, subjective sleep quality and psychomotor vigilance performance were better with BVS. Both CPAP and BVS appear to be equally effective in improving daytime hypercapnia in a subgroup of patients with obesity hypoventilation syndrome without severe nocturnal hypoxaemia. Australian Clinical Trials Registry ACTRN01205000096651.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1371/journal.pone.0001233

PloS one

PLoS One

Acute sleep deprivation and circadian misalignment associated with transition onto the first night of work impairs visual selective attention.

Overnight operations pose a challenge because our circadian biology promotes sleepiness and dissipates wakefulness at night. Since the circadian effect on cognitive functions magnifies with increasing sleep pressure, cognitive deficits associated with night work are likely to be most acute with extended wakefulness, such as during the transition from a day shift to night shift. To test this hypothesis we measured selective attention (with visual search), vigilance (with Psychomotor Vigilance Task [PVT]) and alertness (with a visual analog scale) in a shift work simulation protocol, which included four day shifts followed by three night shifts. There was a nocturnal decline in cognitive processes, some of which were most pronounced on the first night shift. The nighttime decrease in visual search sensitivity was most pronounced on the first night compared with subsequent nights (p = .04), and this was accompanied by a trend towards selective attention becoming 'fast and sloppy'. The nighttime increase in attentional lapses on the PVT was significantly greater on the first night compared to subsequent nights (p<.05) indicating an impaired ability to sustain focus. The nighttime decrease in subjective alertness was also greatest on the first night compared with subsequent nights (p<.05). These nocturnal deficits in attention and alertness offer some insight into why occupational errors, accidents, and injuries are pronounced during night work compared to day work. Examination of the nighttime vulnerabilities underlying the deployment of attention can be informative for the design of optimal work schedules and the implementation of effective countermeasures for performance deficits during night work.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2007.00611.x

Journal of sleep research

J Sleep Res

The trait of Introversion-Extraversion predicts vulnerability to sleep deprivation.

According to Eysenck's theory of Introversion-Extroversion (I-E), introverts demonstrate higher levels of basal activity within the reticular-thalamic-cortical loop, yielding higher tonic cortical arousal than Extraverts, who are described conversely as chronically under-aroused and easily bored. We hypothesized that higher scores on the trait of Extraversion would be associated with greater declines in psychomotor vigilance performance during prolonged wakefulness. We evaluated the relationship between I-E and overnight psychomotor vigilance performance during 77 h of continuous sleep deprivation in a sample of 23 healthy adult military personnel (19 men; four women), ranging in age from 20 to 35 years. At baseline, volunteers completed the Revised NEO Personality Inventory (NEO PI-R) and completed psychomotor vigilance testing at approximately 10-min intervals from 00:15 to 08:50 hours over three nights of continuous sleep deprivation. In addition, 12 participants received four repeated administrations of caffeine (200 mg) every 2 h each night. Analysis of covariance and stepwise multiple regression analyses showed that, above and beyond the effects of caffeine, higher Extraversion was significantly related to more extensive declines in speed of responding and more frequent attentional lapses, but only for the first overnight testing session. Sub-factors of Extraversion, including Gregariousness and higher Activity level were most predictive of these changes following sleep loss. These findings are consistent with Eysenck's cortico-reticular activation theory of I-E and suggest that individual differences in the trait of Extraversion confer some vulnerability/resistance to the adverse effects of sleep loss on attention and vigilance.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/30.10.1334

Sleep

Sleep

The interactive effects of extended wakefulness and low-dose alcohol on simulated driving and vigilance.

Sleep deprivation and alcohol both impair driving performance. This study assessed the interactive effect of low-dose alcohol and extended wakefulness. Repeated-measures, crossover design evaluating psychomotor and driving function in a non-sleep-deprived state and after extended wakefulness with and without low-dose alcohol. Teaching hospital sleep laboratory. Nineteen volunteer professional drivers. Driving simulation (AusEd) and the Psychomotor Vigilance Task (PVT) were measured in a rested state (12-15 hours awake) and after extended wakefulness (18-21 hours awake) during two sessions. Alcohol was administered during one session, with performance measured at blood alcohol concentrations (BAC) of 0.00%, 0.03%, and 0.05% in a non-sleep-deprived state, and at 0.03% after extended wakefulness (at 01:00 and 03:00). During the second session, tests were performed at the same times without alcohol. The combination of extended wakefulness and low-dose alcohol had significant deleterious effects on reaction time and lapses (PVT) and variation in lane position and speed (AusEd). Extended wakefulness (18-21 hours awake) combined with low-dose alcohol (0.03% BAC) resulted in more lapses (t = -2.75, P < 0.05) and greater variation in lane position (t = -3.94, P < 0.01) and speed (t = -2.79, P < 0.05) than did a BAC of 0.05% in a rested state. The combination of legal low-dose alcohol and extended wakefulness results in impairment worse than that at an alcohol level known to increase accident risk. Avoiding alcohol when driving after extended wakefulness may reduce accident risk.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/30.10.1309

Sleep

Sleep

Sleep-disordered breathing and psychomotor vigilance in a community-based sample.

Sleep-disordered breathing (SDB) has been associated with impaired psychomotor vigilance performance in patients with sleep apnea patients. A bias toward greater referral of sleep apnea patients with severely impaired performance could explain these findings. Furthermore, no studies on the association between SDB and vigilance performance in a large community-based sample have been reported that encompasses the full spectrum of SDB severity. This study investigated the association between SDB and psychomotor vigilance with cross-sectional data from the Wisconsin Sleep Cohort Study. Community-based sample of 265 women and 346 men, mean age of 53.0 +/- 7.9 (age range: 35-74) years was used. Within 6 months of completing an overnight polysomnography protocol for SDB assessment, participants completed a 10-minute psychomotor vigilance task (PVT) during a daytime protocol. Sleep-disordered breathing was indicated by the number of apneas and hypopneas; psychomotor vigilance task variables included (1) mean of 1/reaction time (RT), (2) number of lapses, (3) mean reciprocal of fastest 10% RTs, (4) mean reciprocal of slowest 10% RTs, (5) slope of linear regression line across the 10 minutes of the task fit to 1/RTs, and (5) number of false responses. Multiple regression analysis showed a significant negative association between the logarithmically transformed apnea-hypopnea index (LogAHI) and number of lapses, mean of the slowest 10%, and number of false responses from the psychomotor vigilance task, independent of sex and body mass index in participants aged 65 years and older. SDB in the community population is associated with impaired psychomotor vigilance in older men and women.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.2466/pms.105.1.276-286

Perceptual and motor skills

Percept Mot Skills

Lack of degradation in visuospatial perception of line orientation after one night of sleep loss.

Sleep deprivation impairs a variety of cognitive abilities including vigilance, attention, and executive function. Although sleep loss has been shown to impair tasks requiring visual attention and spatial perception, it is not clear whether these deficits are exclusively a function of reduced attention and vigilance or if there are also alterations in visuospatial perception. Visuospatial perception and sustained vigilance performance were therefore examined in 54 healthy volunteers at rested baseline and again after one night of sleep deprivation using the Judgment of Line Orientation Test and a computerized test of psychomotor vigilance. Whereas psychomotor vigilance declined significantly from baseline to sleep-deprived testing, scores on the Judgment of Line Orientation did not change significantly. Results suggest that documented performance deficits associated with sleep loss are unlikely to be the result of dysfunction within systems of the brain responsible for simple visuospatial perception and processing of line angles.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/30.9.1195

Sleep

Sleep

Nocturnal hypoxia exposure with simulated altitude for 14 days does not significantly alter working memory or vigilance in humans.

To assess the effect of 2 weeks of nocturnal hypoxia exposure using simulated altitude on attention and working memory in healthy adult humans. Prospective experimental physiological assessment. General Clinical Research Center. Eleven healthy, nonsmoking, subjects (7 men, 4 women). The subjects had a mean age of 27 +/- 1.5 years and body mass index of 23 +/- 0.9 kg/m2. Subjects were exposed to 9 hours of continuous hypoxia from 2200 to 0700 hours in an altitude tent. Acclimatization was accomplished by graded increases in "altitude" over 3 nights (7700, 10,000 and 13,000 feet), followed by 13,000 feet for 13 consecutive days (FIO2 0.13). Polysomnography that included airflow measurements with a nasal cannula were done at baseline and during 3 time points across the protocol (nights 3, 7, and 14). Attention (10-minute Psychomotor Vigilance Task) and working memory (10-minute verbal 2-back) were assessed at baseline and on day 4, 8, 9, and 15. Nocturnal hypoxia was documented using endpoints of minimum oxygen saturation, oxygen desaturation index, and percentage of total sleep time under 90% and 80%. Total sleep time was reduced, stage 1 sleep was increased, and both obstructive and nonobstructive respiratory events were induced by altitude exposure. There was no difference in subjective mood, attention, or working memory. Two weeks of nocturnal continuous hypoxia in an altitude tent did not induce subjective sleepiness or impair objective vigilance and working memory. Caution is recommended in the extrapolation to humans the effects of hypoxia in animal models.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/30.9.1129

Sleep

Sleep

Optimization of biomathematical model predictions for cognitive performance impairment in individuals: accounting for unknown traits and uncertain states in homeostatic and circadian processes.

Current biomathematical models of fatigue and performance do not accurately predict cognitive performance for individuals with a priori unknown degrees of trait vulnerability to sleep loss, do not predict performance reliably when initial conditions are uncertain, and do not yield statistically valid estimates of prediction accuracy. These limitations diminish their usefulness for predicting the performance of individuals in operational environments. To overcome these 3 limitations, a novel modeling approach was developed, based on the expansion of a statistical technique called Bayesian forecasting. The expanded Bayesian forecasting procedure was implemented in the two-process model of sleep regulation, which has been used to predict performance on the basis of the combination of a sleep homeostatic process and a circadian process. Employing the two-process model with the Bayesian forecasting procedure to predict performance for individual subjects in the face of unknown traits and uncertain states entailed subject-specific optimization of 3 trait parameters (homeostatic build-up rate, circadian amplitude, and basal performance level) and 2 initial state parameters (initial homeostatic state and circadian phase angle). Prior information about the distribution of the trait parameters in the population at large was extracted from psychomotor vigilance test (PVT) performance measurements in 10 subjects who had participated in a laboratory experiment with 88 h of total sleep deprivation. The PVT performance data of 3 additional subjects in this experiment were set aside beforehand for use in prospective computer simulations. The simulations involved updating the subject-specific model parameters every time the next performance measurement became available, and then predicting performance 24 h ahead. Comparison of the predictions to the subjects' actual data revealed that as more data became available for the individuals at hand, the performance predictions became increasingly more accurate and had progressively smaller 95% confidence intervals, as the model parameters converged efficiently to those that best characterized each individual. Even when more challenging simulations were run (mimicking a change in the initial homeostatic state; simulating the data to be sparse), the predictions were still considerably more accurate than would have been achieved by the two-process model alone. Although the work described here is still limited to periods of consolidated wakefulness with stable circadian rhythms, the results obtained thus far indicate that the Bayesian forecasting procedure can successfully overcome some of the major outstanding challenges for biomathematical prediction of cognitive performance in operational settings.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.apmr.2007.07.012

Archives of physical medicine and rehabilitation

Arch Phys Med Rehabil

Cognitive impairment in patients with traumatic brain injury and obstructive sleep apnea.

To examine the impact of comorbid obstructive sleep apnea (OSA) on the cognitive functioning of traumatic brain injury (TBI) patients. A case-control study. Neuropsychologic test performances of TBI patients with OSA were compared with those who did not have OSA. The diagnosis of OSA was based on standard criteria using nocturnal polysomnography. Three academic medical centers with level I trauma centers, accredited sleep disorders centers, and rehabilitation medicine programs. Thirty-five TBI patients who were part of a project that assessed the effect of sleep disorders in a larger sample of consecutively recruited TBI patients. There were 19 patients with TBI and OSA. They were compared with 16 TBI patients without OSA who were comparable in terms of age, education, severity of injury (when available), time postinjury, and Glasgow Coma Scale scores (when available). Not applicable. The Psychomotor Vigilance Test, Rey Complex Figure Test, Rey Auditory Verbal Learning Test, digit span test from the Wechsler Memory Scale-Revised, and finger-tapping test. The TBI patients with OSA performed significantly worse than the non-sleep disordered TBI patients on verbal and visual delayed-recall measures. The groups performed comparably on motor, visual construction, and attention tests. The TBI patients with OSA made more attention lapses (reaction times >/=500ms), but showed comparable fastest and slowest reaction times on a measure of sustained attention. OSA is associated with more impairment of sustained attention and memory in TBI patients. It is possible that early identification and treatment of OSA may improve cognitive, and thus potentially functional, outcomes of TBI patients with this disease.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Aviation, space, and environmental medicine

Aviat Space Environ Med

Rapid counterclockwise shift rotation in air traffic control: effects on sleep and night work.

In Air Traffic Control, counterclockwise rapidly rotating shift schedules are often employed but may result in significant sleep loss. This has potential consequences for performance, particularly if a night shift is worked. As part of a large-scale field study, the pattern of sleep across a 4-d counterclockwise, rapidly rotating schedule (afternoon, day, morning, night shift) was documented and relationships between prior sleep and performance during the night shift were investigated. There were 28 controllers who completed 4 periods of data collection which included 2 d before and 2 d after a 4-d shift cycle. Sleep was recorded using an actigraph and sleep diary, and performance on each night shift was measured three times using the Psychomotor Vigilance Task. Across the work week, sleep duration decreased largely due to earlier rise times associated with shift start times moving backward. In the short turn-around between the morning and night shift, 90% of controllers slept for an average of 2.2 h. Improved performance on the night shift was related only to longer periods of sleep the night prior. This study demonstrates that a 4-d counterclockwise, rapidly rotating schedule results in a progressive reduction in sleep and consequently the rapid accumulation of a sleep debt. To help maintain their performance on the night shift, it is recommended that controllers attempt to obtain at least 6 h sleep the night before a night shift. It is also recommended that ATC providers educate their workforce about this issue.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.2486/indhealth.45.552

Industrial health

Ind Health

Impact of nap length, nap timing and sleep quality on sustaining early morning performance.

The study examined how nap length, nap timing and sleep quality affect early morning performance (6:00 to 8:00). Twelve students participated in a simulated nightshift schedule (22:00 to 8:00) where the length and timing of nocturnal naps were manipulated (0:00-1:00, 0:00-2:00, 4:00-5:00 and 4:00-6:00). A performance test battery was administered consisting of a psychomotor vigilance test, a logical reasoning test, and a visual analogue scale for subjective fatigue and sleepiness. The results showed that a 120-min nap sustained early morning performance better than a 60-min nap. Taking a nap earlier or later did not affect the neurobehavioral performance tests, although participants slept more efficiently during naps later in the night shift. A negative effect of a nocturnal nap during the night shift on subsequent daytime and nocturnal sleep was not observed in the sleep architecture. It still remains unclear whether slow wave sleep plays an important role in sustaining early morning performance. In terms of work safety and sleep health, the results suggest that a longer and later nap is beneficial during night shifts.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine

J Clin Sleep Med

Prevalence and consequences of sleep disorders in traumatic brain injury.

Determine prevalence and consequences of sleepiness and sleep disorders after traumatic brain injury (TBI). Prospective evaluation with polysomnography (PSG), multiple sleep latency test (MSLT), Epworth Sleepiness Scale (ESS) and neuropsychological testing including Psychomotor Vigilance Test (PVT), Profile of Mood States (POMS), and Functional Outcome of Sleep Questionnaire (FOSQ). Three academic medical centers with level I trauma centers, accredited sleep disorders centers, and rehabilitative medicine programs. Participants; Eighty-seven (87) adults at least 3 months post TBI. Abnormal sleep studies were found in 40 subjects (46%), including 20 (23%) with obstructive sleep apnea (OSA), 10 (11%) with posttraumatic hypersomnia (PTH), 5 (6%) with narcolepsy, and 6 (7%) with periodic limb movements in sleep (PLMS). Among all subjects, 22 (25%) were found to have objective excessive daytime sleepiness with MSLT score <10 minutes. There was no correlation between ESS score and MSLT (r = 0.10). There were no differences in age, race, sex, or education between the sleepy and non-sleepy subjects. Likewise, there were no differences in severity of injury or time after injury between sleepy and non-sleepy subjects. Sleepy subjects had a greater body mass index (BMI) than those who were not sleepy (p = 0.01). OSA was more common in obese subjects (BMI > or =30, p < 0.001). Sleepy subjects demonstrated poorer PVT scores (p < 0.05), better self-reported sleep related quality of life (FOSQ scores [p < 0.05]), and no differences in POMS. There is a high prevalence of sleep disorders (46%) and of excessive daytime sleepiness (25%) in subjects with TBI. Sleepy subjects may be more impaired than comparable non-sleepy TBI subjects, yet be unaware of problems. Given the high prevalence of OSA (23%), PTH (11%), and narcolepsy (7%) in this population, there is a clinical indication for NPSG and MSLT.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1530-0277.2007.00434.x

Alcoholism, clinical and experimental research

Alcohol Clin Exp Res

Effects of a moderate evening alcohol dose. II: performance.

This second of a pair of papers investigates the effects of a moderate dose of alcohol and staying up late on driving simulation performance and simple visual reaction time (RT) at a known circadian phase in well-rested young adults. Twenty-nine adults (9 males), ages 21 to 25 years, spent 1 week on an at-home stabilization schedule of 8.5 to 9 hours, followed by 3 nonconsecutive nights in-lab: adaptation, placebo, and alcohol. Performance task practice occurred on 3 occasions before the study. Alcohol (vodka; 0.54 g/kg men; 0.49 g/kg women mixed with tonic) was consumed over 30 minutes ending 1 hour before normal bedtime; the same quantity of beverage was given on placebo. Driving simulation (with drive-only and dual-task drive and subtract components) and psychomotor vigilance task (PVT) testing occurred before and after alcohol/placebo ingestion. Breath alcohol concentration (BrAC) readings were taken before all test sessions. Saliva samples were taken approximately every 30 minutes to determine circadian phase. Driving simulation and PVT variables significantly deteriorated with increasing time awake. Driving simulator lane variability was worse with alcohol compared with placebo at 15.5 hours awake. No PVT variable showed an effect of alcohol. Driving simulation performance deteriorated with extended waking and with alcohol; driving was most impaired at the peak alcohol level. The PVT, less complex than the driving simulation, did not show effects of alcohol, a finding consistent with previous literature that disruptive effects of low alcohol concentrations increase with task complexity. Overall, simulated driving performance is significantly impaired late at night when even a moderate dose of alcohol is consumed.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/30.3.353

Sleep

Sleep

The characteristics of recovery sleep when recovery opportunity is restricted.

The aim of this study was to investigate the recovery of sleep and waking functions following one night of total sleep deprivation, when recovery opportunity was either augmented or restricted. The 9-day laboratory study involved a baseline night, a night of sleep loss (approximately 40 h) followed by 5 nighttime recovery sleep periods. Recovery consisted of either five 9-h sleep opportunities or five 6-h sleep opportunities. All data collection took place in a controlled laboratory environment at the Centre for Sleep Research. A total of n = 20 healthy adults (18-35 yrs) participated in the study. Each sleep period was recorded using a standard polysomnographic EEG montage. Waking functions were assessed every 2 hours during all wake periods, using a 10 minute psychomotor vigilance task (PVT) and a subjective alertness visual analogue scale (VAS). Sleep analyses indicated that across the week TST, SOL, REM, and sleep efficiency varied significantly between the 2 conditions, but amounts of SWS did not. Waking functions in the 9-h condition recovered after one sleep period. In the 6-h condition however, mean response time on the PVT was 10% below baseline and subjective alertness 20% below baseline for the entire recovery period. The results suggest that TST is a key factor in determining recovery. When recovery opportunity is restricted, both sleep variables and measures of waking functions do not recover.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.bbr.2007.02.019

Behavioural brain research

Behav Brain Res

Psychomotor vigilance task performance during total sleep deprivation in young and postmenopausal women.

The objective of this study was to investigate the effects of age on women's performance in the psychomotor vigilance task (PVT) during total sleep deprivation (SD). A total of 46 healthy women volunteered. They belonged to two age groups: young (n=34; age range 19-30 years; 12 without, and 22 with oral contraceptives (OC); early phase of the menstrual cycle) and older (n=12; age range 60-68; postmenopausal; without hormone therapy). During a 40-h total SD, the subjects performed the PVT and the Stanford Sleepiness Scale (SSS) at 2-h intervals. At baseline, the reaction speed of the young women was faster as compared to the older women (Mann-Whitney U-test p<0.01). During SD, all the PVT measures as well as the SSS scores changed similarly in the two age groups, when the baseline performance difference in favour of the young women was taken into account (area under curve analyses, Mann-Whitney U-tests n.s.). No age difference in the time course of the SD-related deterioration in PVT performance or subjective sleepiness was observed. OC use had no effects on any of the measures during SD. After recovery sleep, young women had higher subjective sleepiness scores than older women, the sleepiness scores being highest in young women not taking OCs. In conclusion, in women, aging has no effects on the amount or the time course of the decline in PVT performance caused by total SD. OC use does not significantly affect young women's PVT performance during SD in the early phase of the menstrual cycle.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1007/s11325-007-0103-4

Sleep & breathing = Schlaf & Atmung

Sleep Breath

Normative psychomotor vigilance task performance in children ages 6 to 11--the Tucson Children's Assessment of Sleep Apnea (TuCASA).

Although the psychomotor vigilance task (PVT) is commonly used in sleep and other research settings, normative data for PVT performance in children have not been published. This report presents normal PVT performance measures among children without a sleep disorder participating in the Tucson Children's Assessment of Sleep Apnea (TuCASA) study. TuCASA is a community-based, prospective study of sleep-disordered breathing in Caucasian and Hispanic children ages 6 to 11 years. A standard 10-min PVT trial was completed by 360 participants-48% female and 36% Hispanic; mean age 8.9 years. Detailed analyses were performed for 162 children with respiratory disturbance indices <1 and no parent-reported sleep problems. Mean and median reaction times (RT) decreased with increasing age (p trend < 0.001). Children ages 6 and 11 had median RTs of 544.24 and 325.70 ms, respectively. Standard deviations in RTs also decreased with increasing age (p trend = 0.001), as did lapses (p trend < 0.001), but no trend was apparent in total errors. There were statistically significant (p = 0.006) differences in the performance of boys and girls. Gender differences were greatest at age 6, where boys had shorter RTs, and decreased with age until performance was approximately equal by age 11. No ethnic differences were detected. Children's PVT performance improves with age and differs by gender. These differences should be considered when the PVT is utilized in pediatric populations.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.2466/pms.103.3.883-886

Perceptual and motor skills

Percept Mot Skills

Trait-anger enhances effects of caffeine on psychomotor vigilance performance.

This study examined the combined effects of caffeine and the personality attribute of trait-anger on the speed of psychomotor vigilance performance during sleep deprivation. 23 young adult soldiers (19 male) were administered the State-Trait Anger Expression Inventory-2 when well-rested. Participants were then sleep deprived for three consecutive nights (77 hours total) during which they completed repeated psychomotor vigilance testing. Half of the participants received four doses of oral caffeine (200 mg every 2 hr.; 800 mg total) each night, while the other half were administered a placebo. For the first night, higher scores on trait-anger, outward anger expression, and intensity of anger expression predicted better sustained overnight vigilance performance, but only for those volunteers receiving caffeine. These correlations were not significant for the subsequent nights. Findings suggest a possible synergistic effect between personality traits associated with arousal of the central nervous system and vigilance-promoting effects of caffeine.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1515/BMT.2007.015

Biomedizinische Technik. Biomedical engineering

Biomed Tech (Berl)

Vigilance monitoring--review and practical aspects.

Vigilance monitoring is increasingly important in the industrialised world because working tasks are becoming increasingly monotonous and less physically exhausting, resulting in a high risk of falling asleep unintentionally. Among existing tests for the assessment of vigilance, objectiveness plays the most important role in preventing volitional influence by the test subject. In addition, the tests should be simple so that a monotonous situation will emerge. This review gives an overview of important vigilance monitoring systems that are currently in use for research purposes and industrial application. The tests presented are the Mackworth clock test, the VIGIMAR, the Karolinska drowsiness test, tests based on blood pressure and heart rate changes, the psychomotor vigilance test, and experimental tests relying on pupillography and electrodermal activity.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1093/sleep/30.1.96

Sleep

Sleep

Time-on-task impairment of psychomotor vigilance is affected by mild skin warming and changes with aging and insomnia.

To investigate the effect of mild manipulations of core and skin temperature on psychomotor vigilance (PVT) in young adults, elderly, and elderly insomniacs. 432 PVTs were obtained during a 2-day semi-constant routine protocol, while differentially manipulating core and skin temperatures within a comfortable thermoneutral range. Sleep laboratory of the Netherlands Institute for Neuroscience. Groups of 8 sex-matched young adults (27.0 +/- 2.4 years, mean +/- s.e.m.), elderly (65.8 +/- 2.8 years), and insomniacs (59.1 +/-1.9 years). During the 7-minute PVTs, response speed typically declined with increasing time-on-task. Proximal skin warming by only +/- 0.6 degrees C accelerated this decline by 67% (P = 0.05) in young adults and by 50% (P < 0.05) in elderly subjects. In elderly insomniacs, proximal warming slowed down the mean response speed already from the onset of the task (3% level drop, P < 0.001). Response speed tended to decrease with age (P < 0.10), reaching significance only in elderly insomniacs (P < 0.05). Speed decrements occurred mostly towards the end of the time-on-task in young adults; earlier and more gradually in elderly without sleep complaints; and very early and in a pronounced fashion in insomniacs. Interestingly, the worsening by warming followed the time pattern already present within each group. The results are compatible with the hypothesis that the endogenous circadian variation of skin temperature could modulate vigilance regulating brain areas and thus contribute to the circadian rhythm in vigilance. Minute-by-minute PVT analyses revealed effects of age and insomnia not previously disclosed in studies applying time-point aggregation. Our data indicate that "age-related cognitive slowing" may result, in part, from age-related sleep problems.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2007.00574.x

Journal of sleep research

J Sleep Res

The dynamics of neurobehavioural recovery following sleep loss.

Rate of recovery of daytime performance and sleepiness following moderate and severe sleep deprivation (SD) was examined when recovery opportunity was either augmented or restricted. Thirty healthy non-smokers, aged 18-33 years, participated in one of three conditions: moderate SD with augmented (9-h) recovery opportunities, moderate SD with restricted (6-h) recovery opportunities, or severe SD with augmented recovery opportunities. Each participant attended the laboratory for 8-9 consecutive nights: an adaptation and baseline night (23:00-08:00 hours), one or two night(s) of wakefulness, and five consecutive recovery sleep opportunities (23:00-08:00 hours or 02:00-08:00 hours). On each experimental day, psychomotor vigilance performance (PVT) and subjective sleepiness (SSS) were assessed at two-hourly intervals, and MSLTs were performed at 1000 h. PSG data was collected for each sleep period. For all groups, PVT performance significantly deteriorated during the period of wakefulness, and sleepiness significantly increased. Significant differences were observed between the groups during the recovery phase. Following moderate SD, response speed, lapses and SSS returned to baseline after one 9-h sleep opportunity, while sleep latencies required two 9-h opportunities. When the recovery opportunity was restricted to six hours, neither PVT performance nor sleepiness recovered, but stabilised at below-baseline levels. Following severe SD, sleepiness recovered after one (SSS) or two (physiological) 9-h sleep opportunities, however PVT performance remained significantly below baseline for the entire recovery period. These results suggest that the mechanisms underlying the recovery process may be more complicated than previously thought, and that we may have underestimated the impact of sleep loss and/or the restorative value of subsequent sleep.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1185/030079906X167363

Current medical research and opinion

Curr Med Res Opin

Effects of desloratadine and alcohol coadministration on psychomotor performance.

This study was set up to evaluate the effects of desloratadine 7.5 mg daily, with and without alcohol, on sedation and psychomotor performance. In a double-blind, placebo-controlled, four-way crossover trial, 25 adult patients were randomized to desloratadine 7.5 mg, desloratadine 7.5 mg plus alcohol, placebo, or placebo plus alcohol. Alcohol was weight adjusted to an average blood alcohol concentration of 0.1%. Assessments included the modified Romberg test, Stanford Sleepiness Scale, Digit Symbol Substitution Test, Serial Add Subtract Reaction Time Test, and the Psychomotor Vigilance Test. The primary variable was the mean score of each of the five tests averaged over the treatment period, expressed as the mean percent change from baseline. Across these assessments, differences between desloratadine alone or with alcohol versus placebo alone or without alcohol, were not significant, whereas most differences between desloratadine and placebo alone versus desloratadine and placebo with alcohol were significant (p < 0.01). Thus, with or without alcohol, desloratadine 7.5 mg does not increase sedation or impair psychomotor performance. Most adverse events (AEs) were mild-to-moderate in severity, with the most frequently reported individual AEs being headache, fatigue, nausea, vomiting, and dry mouth. The study does have potential limitations. The measures used are restricted to a particular profile of the known effects of alcohol only, and the relatively high doses of alcohol used alone demonstrate effects on psychomotor function and attention. A single dose of desloratadine does not potentiate alcohol-mediated CNS impairment. Desloratadine alone or in combination with alcohol was safe and well tolerated.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1109/IEMBS.2005.1615790

Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference

Conf Proc IEEE Eng Med Biol Soc

Identification of vigilance lapses using EEG/EOG by expert human raters.

It is critically important for certain occupational groups to remain highly alert throughout their working day. For safety reasons, it would be useful to automatically detect lapses in performance using EEG/EOG. Automating the detection process could be simplified considerably if we could mimic human experts. Surprisingly, it is unclear to what extent human EEG raters are able to detect lapses. Consequently, we undertook a study in which 4 expert EEG raters assessed the level of alertness of 10 air traffic controllers by observing a combination of their EEG and EOG while they performed a 10 min psychomotor vigilance task (PVT). They were specifically required to identify lapses or sleep episodes that might lead to a lapse in PVT performance. A reaction time .. 500 ms was defined as a PVT lapse. There was a total of 101 lapses (mean duration = 1.00 s). Of these, only 6 lapses were detected by one or more raters and all of these were marked as ;sleep'. Overall the human expert raters were unable to reliably identify lapses based only on EEG and EOG. This poor performance suggests an automated system would need to identify subtle features not overtly visible in the EEG.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1080/07420520601067931

Chronobiology international

Chronobiol Int

Can a shorter psychomotor vigilance task be used as a reasonable substitute for the ten-minute psychomotor vigilance task?

The 10 min psychomotor vigilance task (PVT) is commonly used in laboratory studies to assess the impact of sleep loss, sustained wakefulness, and/or time of day on neurobehavioral performance. In field settings, though, it may be impractical for participants to perform a test of this length. The aim of this study was to identify a performance measure that is sensitive to the effects of fatigue but less burdensome than a 10 min test. Sixteen participants (11 female, 5 male; mean age = 21.7 years) slept in the sleep laboratory overnight then remained awake for 28 h from 08:00 h. During every second hour, participants completed three PVTs of differing duration (10 min, 5 min, 90 sec). For the 5 min/10 min comparison, ANOVA indicated that response time was significantly affected by test length (F1,14 = 26.9, p < .001) and hours of wakefulness (F13,182 = 46.1, p < .001) but not by their interaction (F13,182 = 1.7, ns). There was a strong correlation between response time on the 5 and 10 min PVTs (r = .88, p < .001). For the 90 sec/10 min comparison, ANOVA indicated that response time was significantly affected by test length (F1,14 = 65.9, p < .001) and hours of wakefulness (F13,182 = 29.7, p < .001) as well as by their interaction (F13,182 = 6.0, p < .001). There was a strong correlation between response time on the 90 sec and 10 min PVTs (r = .77, p < .001). The effects of hours of wakefulness on neurobehavioral performance were similar for the 5 min and 10 min PVTs. In contrast, performance on the 90 sec PVT was less affected by hours of wakefulness than on the 10 min PVT. In addition, performance on the 10 min PVT was more highly correlated with the 5 min PVT than the 90 sec PVT. These data indicate that the 5 min PVT may provide a reasonable substitute for the 10 min PVT in circumstances where a test shorter than 10 min is required.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1080/07420520601085925

Chronobiology international

Chronobiol Int

The sleep, subjective fatigue, and sustained attention of commercial airline pilots during an international pattern.

International commercial airline pilots may experience heightened fatigue due to irregular sleep schedules, long duty days, night flying, and multiple time zone changes. Importantly, current commercial airline flight and duty time regulations are based on work/rest factors and not sleep/wake factors. Consequently, the primary aim of the current study was to investigate pilots' amount of sleep, subjective fatigue, and sustained attention before and after international flights. A secondary aim was to determine whether prior sleep and/or duty history predicted pilots' subjective fatigue and sustained attention during the international flights. Nineteen pilots (ten captains, nine first officers; mean age: 47.42+/-7.52 years) participated. Pilots wore wrist activity monitors and completed sleep and duty diaries during a return pattern from Australia to Europe via Asia. The pattern included four flights: Australia-Asia, Asia-Europe, Europe-Asia, and Asia-Australia. Before and after each flight, pilots completed a 5 min PalmPilot-based psychomotor vigilance task (PVT) and self-rated their level of fatigue using the Samn-Perelli Fatigue Checklist. Separate repeated-measures ANOVAs were used to determine the impact of stage of flight and flight sector on the pilots' sleep in the prior 24 h, self-rated fatigue, and PVT mean response speed. Linear mixed model regression analyses were conducted to examine the impact of sleep in the prior 24 h, prior wake, duty length, and flight sector on pilots' self-rated fatigue and sustained attention before and after the international flights. A significant main effect of stage of flight was found for sleep in the prior 24 h, self-rated fatigue, and mean response speed (all p < 0.05). In addition, a significant main effect of flight sector on self-rated fatigue was found (p < .01). The interaction between flight sector and stage of flight was significant for sleep in the prior 24 h and self-rated fatigue (both p < .05). Linear mixed model analyses indicated that sleep in the prior 24 h was a significant predictor of self-rated fatigue and mean response speed after the international flight sectors. Flight sector was also a significant predictor of self-rated fatigue. These findings highlight the importance of sleep and fatigue countermeasures during international patterns. Furthermore, in order to minimize the risk of fatigue, the sleep obtained by pilots should be taken into account in the development of flight and duty time regulations.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1080/07420520601062387

Chronobiology international

Chronobiol Int

Do short international layovers allow sufficient opportunity for pilots to recover?

For Australian pilots, short layovers (<40 h) are a feature of many international patterns. However, anecdotal reports suggest that flight crew members find patterns with short slips more fatiguing than those with a longer international layover, as they restrict the opportunity to obtain sufficient sleep. The current study aimed to determine whether pilots operating international patterns with short layovers have sufficient opportunity to recover prior to the inbound flight. Nineteen international pilots (ten captains, nine first officers) operating a direct return pattern from Australia to Los Angeles (LAX) with a short (n = 9) 9+/-0.8 h (mean+/-S.D) or long (n = 10) 62.2+/-0.9 h LAX layover wore an activity monitor and kept a sleep/duty diary during the pattern. Immediately before and after each flight, pilots completed a 5 min PalmPilot-based psychomotor vigilance task (Palm-PVT). Flights were of comparable duration outbound (3.5+/-0.6 h) and inbound (14.3+/-0.6 h) and timing. The amount of sleep obtained in-flight did not significantly vary as a function of layover length. However, pilots obtained significantly more sleep during the inbound (3.7+/-0.8 h) than the outbound flight (2.2+/-0.8 h). Pilots with the shorter layover obtained significantly less sleep in total during layover (14.0+/-2.7 h vs. 19.6+/-2.5), due to significantly fewer sleep periods (3.0+/-0.7 vs. 4.0+/-0.9). However, neither mean sleep duration nor the sleep obtained in the 24 h prior to the inbound flight significantly differed as a function of layover length. Response speed significantly varied across the pattern, and a significant interaction was also observed. For pilots with a short layover, response speed was significantly slower at the end of both the outbound and inbound flight, and prior to the inbound flight (i.e., at the end of layover), relative to response speed at the start of the pattern (pre-trip). Similarly, response speed for the longer layover was slower at the end of the outbound flight compared to pre-trip (approaching significance, p = 0.073). However, response speed at the beginning of the inbound flight was significantly faster than pre-trip and did not significantly differ from pre-trip at the end of the inbound flight. The data suggest that short slips (<40 h) do not allow pilots the opportunity to obtain sufficient sleep to reverse the effects of fatigue accumulated during the outbound flight. As a result, their response speed prior to the inbound flight is substantially slower than the response speed of flight crew with a longer layover.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1080/07420520601083391

Chronobiology international

Chronobiol Int

Self-awareness of impairment and the decision to drive after an extended period of wakefulness.

Fatigue is an increasingly noted factor in road accidents. The ability to predict and be aware of impairment in terms of driving capability is important for potential legal liability and road safety. However, to date, there have been few studies that have investigated the accuracy of individuals in predicting how safely they could drive during conditions of sleep loss. Research has demonstrated that individuals rate themselves as better than the population average in a number of domains, including driving-related skills. Therefore, this study also aimed to investigate self-ratings of predicted driving ability during extended wakefulness and compare them to ratings made of a hypothetical other person under the same conditions. Thirty-two participants remained awake for a period of 40 h. Every 2 h, they completed the Psychomotor Vigilance Task (PVT) and rated on a seven-point scale how well they thought they could drive safely, react quickly in an emergency, and stay in their own lane. They were also asked to assess how they thought someone else in their own position could drive. The participants rated their driving ability as becoming significantly poorer at the same time that their PVT performance became significantly slower. Self-ratings indicating a qualitative assessment of poorer than neutral driving occurred at 03:00 h for both the "drive safely" and "react quickly" questions, after 19 h of continuous wakefulness (starting at 08:00 h). This occurred at 05:00 h for the "keep in my lane" question. Previous studies with a similar protocol demonstrated that under these conditions, individuals exhibit a performance decrements equivalent to someone with a blood alcohol concentration of 0.05% (the legal driving limit in Australia). Participants consistently rated the ability of others to drive as poorer than their own. The main implication from this study for road safety and legal liability is that it is reasonable to focus on a person's perception of the situation, as it does align with objective reality to a certain extent. A concern in terms of road safety is potential overconfidence, indicated by rating others consistently poorer than themselves.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1080/07420520601096443

Chronobiology international

Chronobiol Int

Estimating the circadian rhythm in the risk of occupational injuries and accidents.

The authors recently published a prototypic Risk Index (RI) to estimate the risk of critical errors associated with shift systems. This RI was based on published trends in the relative risk of injuries and accidents, and a simple additive model was proposed to estimate the risk for a given shift system. However, extending the RI to irregular work schedules requires an estimation of the phase and amplitude of the circadian rhythm in risk. This paper integrates the published evidence on three independent sources of data that allow such estimations to be made: the trend in risk over a 24 h day, over the course of the night shift, and across the three different (8 h) shifts. Despite potential confounders, maximum risk (i.e., acrophase = peak time) estimates across these three trends showed a remarkable consistency, with all three estimates occurring at about midnight, although the amplitude estimates varied considerably. The best estimate of the amplitude of the circadian rhythm in risk would appear to be that based on trend over the three (8 h) shifts, as this trend is the least confounded. The estimated acrophase (peak time) in risk appeared earlier than would be predicted from consideration of the circadian rhythm in alertness, fatigue, or performance on simple interpolated tasks, such as reaction time or performance on the Psychomotor Vigilance Test.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.3357/asem.1879.2006

Aviation, space, and environmental medicine

Aviat Space Environ Med

Alertness management in aviation operations: enhancing performance and sleep.

Fatigue is an acknowledged safety risk in diverse operational settings. As a result, there has been growing interest in developing and implementing activities to improve alertness, performance, and safety in real-world operations where fatigue is a factor. A comprehensive Alertness Management Program (AMP) that included education, alertness strategies, scheduling, and healthy sleep was implemented in a commercial airline. An operational evaluation was conducted with 29 flight crewmembers, first when flying a standard schedule without AMP components (i.e., standard condition) compared with full AMP implementation, which included flying an innovative schedule that incorporated physiological sleep and alertness principles (i.e., intervention condition). The evaluation included objective measures of sleep quantity (actigraphy), psychomotor vigilance task (PVT) performance, and subjective reports of daily activities and sleep. The results showed that the 3.5-h educational CD improved pre-education test scores from an average 74% correct to a post-education average of 98%. Alertness strategies showed minimal changes, though the daily diary did not allow for refined evaluation of duration, frequency, and timing of use. The intervention condition was associated with significantly more sleep (1 h, 9 min; p < 0.01) during the trip period compared with the standard schedule. All performance metrics showed significantly better performance during the intervention condition trip schedule (p < 0.01) compared with the standard condition. This first-ever evaluation of a comprehensive AMP showed significantly improved knowledge, support for the use of alertness strategies, and increased sleep and performance during actual operations. The robust and consistent findings support the use of an AMP approach to effectively manage fatigue in operational settings.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

The international tinnitus journal

Int Tinnitus J

Arousal and attention deficits in patients with tinnitus.

We investigated the effects of tinnitus on measures of arousal and attention at various levels of the neuraxis to derive a profile of the pathophysiology of tinnitus. Individuals with tinnitus of at least 6 months' duration (14 male, 15 female) and healthy controls (14 male, 21 female) were tested for arousal and habituation to repetitive stimulation at the brainstem-thalamus level by measuring the P50 potential, a scalp-recorded, auditory-evoked response, using pairs of click stimuli. We used the psychomotor vigilance task, a reaction-time test, to assess attentional processes mediated by thalamocortical functions. We then correlated deficits in arousal and attention, as measured by these tests, with perceived tinnitus severity. Results showed no difference between tinnitus patients and controls in level of arousal or habituation to repetitive sensory stimulation, as measured by the amplitude of the P50 potential and the ability to suppress a second, closely paired stimulus, respectively. However, reaction-time assessments showed that patients with tinnitus have attentional deficits relative to controls (p = .02). We found no significant correlation between sleep disturbance or tinnitus severity and reaction-time testing.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1111/j.1365-2869.2006.00547.x

Journal of sleep research

J Sleep Res

The effects of chewing versus caffeine on alertness, cognitive performance and cardiac autonomic activity during sleep deprivation.

Chewing has been shown to alleviate feelings of sleepiness and improve cognitive performance during the day. This study investigated the effect of chewing on alertness and cognitive performance across one night without sleep as well as the possible mediating role of cardiac autonomic activity. Fourteen adults participated in a randomized, counterbalanced protocol employing a chewing, placebo and caffeine condition. Participants completed tasks assessing psychomotor vigilance, tracking, grammatical reasoning, alertness and sleepiness each hour across the night. All participants received either placebo or caffeine (200 mg), while the chewing condition also chewed on a tasteless and odorless substance for 15 min each hour. Heart rate (HR), root mean square of the successive differences in R-R intervals on the ECG (RMSSD), and preejection period (PEP) were simultaneously recorded. Alertness and cognitive performance amongst the chewing condition did not differ or were in fact worse when compared with placebo. Similarly, measures of HR and RMSSD remained the same between these two conditions; however, PEP was reduced in the later part of the night in the chewing condition compared with a relative increase for placebo. Caffeine led to improved speed and accuracy on cognitive tasks and increased alertness when compared with chewing. Relative increases in RMSSD and reductions in HR were demonstrated following caffeine; however, no change in PEP was seen. Strong associations between cardiac parasympathetic activity and complex cognitive tasks, as well as between subjective alertness and simpler cognitive tasks, suggest a differential process mediating complex versus simple cognitive performance during sleep deprivation.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.physbeh.2006.09.009

Physiology & behavior

Physiol Behav

Circadian rhythms in cognitive performance: methodological constraints, protocols, theoretical underpinnings.

The investigation of time-of-day effects on cognitive performance began in the early days of psychophysiological performance assessments. Since then, standardised, highly controlled protocols (constant routine and forced desynchrony) and a standard performance task (psychomotor vigilance task) have been developed to quantify sleep-wake homeostatic and internal circadian time-dependent effects on human cognitive performance. However, performance assessment in this field depends on a plethora of factors. The roles of task difficulty, task duration and complexity, the performance measure per se, practice effects, inter-individual differences, and ageing are all relevant aspects. Therefore, well-defined theoretical approaches and standard procedures are needed for tasks pinpointing higher cortical functions along with more information about time-dependent changes in the neural basis of task performance. This promises a fascinating challenge for future research on sleep-wake related and circadian aspects of different cognitive domains.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1016/j.annemergmed.2006.02.005

Annals of emergency medicine

Ann Emerg Med

Improving alertness and performance in emergency department physicians and nurses: the use of planned naps.

We examine whether a 40-minute nap opportunity at 3 AM can improve cognitive and psychomotor performance in physicians and nurses working 12-hour night shifts. This is a randomized controlled trial of 49 physicians and nurses working 3 consecutive night shifts in an academic emergency department. Subjects were randomized to a control group (no-nap condition=NONE) or nap intervention group (40-minute nap opportunity at 3 AM=NAP). The main outcome measures were Psychomotor Vigilance Task, Probe Recall Memory Task, CathSim intravenous insertion virtual reality simulation, and Profile of Mood States, which were administered before (6:30 PM), during (4 AM), and after (7:30 AM) night shifts. A 40-minute driving simulation was administered at 8 AM and videotaped for behavioral signs of sleepiness and driving accuracy. During the nap period, standard polysomnographic data were recorded. Polysomnographic data revealed that 90% of nap subjects were able to sleep for an average of 24.8 minutes (SD 11.1). At 7:30 AM, the nap group had fewer performance lapses (NAP 3.13, NONE 4.12; p<0.03; mean difference 0.99; 95% CI: -0.1-2.08), reported more vigor (NAP 4.44, NONE 2.39; p<0.03; mean difference 2.05; 95% CI: 0.63-3.47), less fatigue (NAP 7.4, NONE 10.43; p<0.05; mean difference 3.03; 95% CI: 1.11-4.95), and less sleepiness (NAP 5.36, NONE 6.48; p<0.03; mean difference 1.12; 95% CI: 0.41-1.83). They tended to more quickly complete the intravenous insertion (NAP 66.40 sec, NONE 86.48 sec; p=0.10; mean difference 20.08; 95% CI: 4.64-35.52), exhibit less dangerous driving and display fewer behavioral signs of sleepiness during the driving simulation. Immediately after the nap (4 AM), the subjects scored more poorly on Probed Recall Memory (NAP 2.76, NONE 3.7; p<0.05; mean difference 0.94; 95% CI: 0.20-1.68). A nap at 3 AM improved performance and subjective report in physicians and nurses at 7:30 AM compared to a no-nap condition. Immediately after the nap, memory temporarily worsened. The nap group did not perform any better than the no-nap group during a simulated drive home after the night shift.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1523/JNEUROSCI.1538-06.2006

The Journal of neuroscience : the official journal of the Society for Neuroscience

J Neurosci

Adenosinergic mechanisms contribute to individual differences in sleep deprivation-induced changes in neurobehavioral function and brain rhythmic activity.

Large individual differences characterize the changes induced by sleep deprivation on neurobehavioral functions and rhythmic brain activity. To investigate adenosinergic mechanisms in these differences, we studied the effects of prolonged waking and the adenosine receptor antagonist caffeine on sustained vigilant attention and regional electroencephalogram (EEG) power in the ranges of theta activity (6.25-8.25 Hz) in waking and the slow oscillation (<1 Hz) in sleep. Activity in these frequencies is functionally related to sleep deprivation. In 12 subjectively caffeine-sensitive and 10 -insensitive young men, psychomotor vigilance task (PVT) performance and EEG were assessed at 3 h intervals before, during, and after one night without sleep. After 11 and 23 h waking, subjects received 200 mg caffeine and placebo in double-blind, cross-over manner. In the placebo condition, sleep deprivation impaired PVT speed more in caffeine-sensitive than in caffeine-insensitive men. This difference was counteracted by caffeine. Theta power in waking increased more in a frontal EEG derivation than in a posterior derivation. Caffeine attenuated this power gradient in caffeine sensitive subjects. Sleep loss also differently affected the power distribution <1 Hz in non-rapid eye movement sleep between caffeine sensitive and insensitive subjects. Also, this difference was mirrored by the action of caffeine. The effects of sleep deprivation and caffeine on sustained attention and regional EEG power in waking and sleep were inversely related. These findings suggest that adenosinergic mechanisms contribute to individual differences in waking-induced impairment of neurobehavioral performance and functional aspects of EEG topography associated with sleep deprivation.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1097/01.mlg.0000234936.82619.69

The Laryngoscope

Laryngoscope

Repetitive transcranial magnetic stimulation for tinnitus: a case study.

Correlate subjective improvements in tinnitus severity with restoration of cortical symmetry and sustained attention after neuronavigated low-frequency, repetitive transcranial magnetic stimulation (rTMS). Case study. Positron emission tomography and computed tomography imaging (PET-CT) guided rTMS was performed on a 43-year-old white male with more than a 30 year history of bilateral tinnitus. rTMS was administered to the area of increased cortical activation visualized on PET-CT at a rate of 1 Hz for 30 minutes (1,800 pulses/session) for each of 5 consecutive days, with optimization applied on day 5 using single pulses of TMS to temporarily alter tinnitus perception. Subjective tinnitus severity was rated before and after rTMS using the tinnitus severity index with analogue scale. Attention and vigilance were assessed before and after therapy using the psychomotor vigilance task (PVT), a simple reaction time test that is sensitive to thalamocortical contributions to sustained attention. Posttherapy PET-CT was used to evaluate any change in asymmetric cortical activation. The most marked reduction in tinnitus severity occurred after rTMS optimization; this persisted up to 4 weeks after rTMS. PVT testing showed the patient exhibited a statistically significant improvement in mean slowest 10% reaction times after rTMS (P = .004). PET-CT imaging 2 days after the cessation of rTMS showed no changes in cortical blood flow or metabolic asymmetries. Low-frequency rTMS applied to the primary auditory cortex can reduce tinnitus severity, with rTMS optimization yielding the most favorable results. Beneficial changes occurring in the patient's slowest reaction times suggest that attentional deficits associated with tinnitus may also respond to low-frequency rTMS.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task

10.1152/ajpendo.00651.2005

American journal of physiology. Endocrinology and metabolism

Am J Physiol Endocrinol Metab

Daytime napping after a night of sleep loss decreases sleepiness, improves performance, and causes beneficial changes in cortisol and interleukin-6 secretion.

Sleep loss has been associated with increased sleepiness, decreased performance, elevations in inflammatory cytokines, and insulin resistance. Daytime napping has been promoted as a countermeasure to sleep loss. To assess the effects of a 2-h midafternoon nap following a night of sleep loss on postnap sleepiness, performance, cortisol, and IL-6, 41 young healthy individuals (20 men, 21 women) participated in a 7-day sleep deprivation experiment (4 consecutive nights followed by a night of sleep loss and 2 recovery nights). One-half of the subjects were randomly assigned to take a midafternoon nap (1400-1600) the day following the night of total sleep loss. Serial 24-h blood sampling, multiple sleep latency test (MSLT), subjective levels of sleepiness, and psychomotor vigilance task (PVT) were completed on the fourth (predeprivation) and sixth days (postdeprivation). During the nap, subjects had a significant drop in cortisol and IL-6 levels (P < 0.05). After the nap they experienced significantly less sleepiness (MSLT and subjective, P < 0.05) and a smaller improvement on the PVT (P < 0.1). At that time, they had a significant transient increase in their cortisol levels (P < 0.05). In contrast, the levels of IL-6 tended to remain decreased for approximately 8 h (P = 0.1). We conclude that a 2-h midafternoon nap improves alertness, and to a lesser degree performance, and reverses the effects of one night of sleep loss on cortisol and IL-6. The redistribution of cortisol secretion and the prolonged suppression of IL-6 secretion are beneficial, as they improve alertness and performance.

CognitiveTask

PVT_-_Psychomotor_Vigilance_task