Psychomotor Vigilance Task Test Research Articles

Paraxanthine provides greater improvement in cognitive function than caffeine after performing a 10-km run.

Intense exercise promotes fatigue and can impair cognitive function, particularly toward the end of competition when decision-making is often critical for success. For this reason, athletes often ingest caffeinated energy drinks prior to or during exercise to help them maintain focus, reaction time, and cognitive function during competition. However, caffeine habituation and genetic sensitivity to caffeine (CA) limit efficacy. Paraxanthine (PX) is a metabolite of caffeine reported to possess nootropic properties. This study examined whether ingestion of PX with and without CA affects pre- or post-exercise cognitive function. 12 trained runners were randomly assigned to consume in a double-blind, randomized, and crossover manner 400 mg of a placebo (PL); 200 mg of PL + 200 mg of CA; 200 mg of PL + 200 mg of PX (ENFINITY®, Ingenious Ingredients); or 200 mg PX + 200 mg of CA (PX+CA) with a 7-14-day washout between treatments. Participants donated fasting blood samples and completed pre-supplementation (PRE) side effects questionnaires, the Berg-Wisconsin Card Sorting Test (BCST), and the Psychomotor Vigilance Task Test (PVTT). Participants then ingested the assigned treatment and rested for 60 minutes, repeated tests (PRE-EX), performed a 10-km run on a treadmill at a competition pace, and then repeated tests (POST-EX). Data were analyzed using General Linear Model (GLM) univariate analyses with repeated measures and percent changes from baseline with 95% confidence intervals. BCST correct responses in the PX treatment increased from PRE-EX to POST-EX (6.8% [1.5, 12.1], p = 0.012). The error rate in the PL (23.5 [-2.8, 49.8] %, p = 0.078) and CA treatment (31.5 [5.2, 57.8] %, p = 0.02) increased from PRE-EX values with POST-EX errors tending to be lower with PX treatment compared to CA (-35.7 [-72.9, 1.4] %, p = 0.059). POST-EX perseverative errors with PAR rules were significantly lower with PX treatment than with CA (-26.9 [-50.5, -3.4] %, p = 0.026). Vigilance analysis revealed a significant interaction effect in Trial #2 mean reaction time values (p = 0.049, = 0.134, moderate to large effect) with POST-EX reaction times tending to be faster with PX and CA treatment. POST-EX mean reaction time of all trials with PX treatment was significantly faster than PL (-23.2 [-43.4, -2.4] %, p = 0.029) and PX+CA (-29.6 [-50.3, -8.80] %, p = 0.006) treatments. There was no evidence that PX ingestion adversely affected ratings of side effects associated with stimulant intake or clinical blood markers. Results provide some evidence that pre-exercise PX ingestion improves prefrontal cortex function, attenuates attentional decline, mitigates cognitive fatigue, and improves reaction time and vigilance. Adding CA to PX did not provide additional benefits. Therefore, PX ingestion may serve as a nootropic alternative to CA.

The Influence of a Warm-Up on Vigilance in University Students.

The present study aimed to analyze the effects of conducting a warm-up (WC) or not (WWC) on students of the Science Degree in Physical Activity and Sport before starting a practical class. Thirty-two students of the Science Degree in Physical Activity and Sport (age: 22.38 ± 1.81 years; height: 176.09 ± 8.52 cm; weight: 22.38 ± 1.81 kg; body fat: 25.17 ± 3.20%) participated in a counterbalanced cross-sectional study in which three conditions were tested: (a)basal lineal, (b)WC, and (c)WWC. Participants recorded longer times (worse performance) in the Illinois dribbling test (basal lineal condition [20.17 ± 1.35], WWC [20.13 ± 1.37], and WC [19.32 ± 1.35]) and the Psychomotor Vigilance Task test (basal lineal condition [397.88 ± 75.98ms]; WWC [412.19 ± 91.39ms], and WC [368.53 ± 68.65ms]). The warm-up prior to physical activity classes had positive effects on vigilance linked to executive functioning, and physical performance. In this sense, more research on different types of warm-up may be in order to contrast them with each other, as well as to carry out attention measurements according to the content to be imparted after the warm-ups. The present study represents a big opportunity for all physical education teachers due to warm-up is a crucial aspect that occurs in all practical sessions, also linked to the attention processes and motivational factors of the students.

Comparing the association between heavy metals and cognitive status and depression in miners and non-miners: A study from southeast of Iran

Heavy metal toxicity is a major public health crisis worldwide, especially in mining environments. The association between chronic heavy metals exposure and cognitive impairment has not been studied broadly in adults and mining fields. This study aimed to compare the association between arsenic (As), lead (Pb), and copper (Cu) concentration in blood and cognitive status and depression in copper miners and non-miners. Participants were selected from the Rafsanjan cohort study (RCS) as non-miners and miners from Sarcheshmeh Copper Complex. For evaluation of cognitive performance and creativity, comprehensive neurological tests were performed as follows: Mini-Mental Status Examination (MMSE), Paced Auditory Serial Addition Test (PASAT), Symbol Digit Modalities Test (SDMT), Psychomotor Vigilance Task (PVT), creativity tests including remote association task (RAT) and alternative uses task (AUT). Beck Depression Inventory-II was used to evaluate depression. Standard laboratory tests were also performed. Atomic absorption spectrophotometry was used to estimate the blood's concentration of As, Pb and Cu. We observed a significant difference between arsenic, lead, copper, and depression scores (all P < 0.001) in the two groups (miners and non-miners). Miners had a better performance in cognitive fields except in MMSE and PVT tests. Linear regression analyses showed that the lead had a negative association with the PVT test and depression score. The results suggest that the development of depression, cognitive impairments, and other health problems is possible in chronic heavy metal exposure, especially lead (Pb). Confirmation of our claim requires further study in the coming years.

The effect of selected rest break activities on reaction time, balance, and perceived discomfort after one hour of simulated occupational whole-body vibration exposure in healthy adults

Background & Objective : Negative health effects from occupational whole-body vibration (WBV) exposure during machinery operation include alterations in proprioception, vestibular function, reaction time, stress, motor response, and decrements in musculoskeletal health. To reduce WBV exposure during machinery operation, it may be possible to incorporate short rest break activities throughout the day. This study aims to determine if there are intervention activities that can minimize decrements in cognitive, proprioceptive, and musculoskeletal effects related to WBV exposure during machine operation. Materials & Methods Eleven healthy adults participated in four 1-hour sessions of ecologically valid WBV exposure followed by one of four 5-minute activities: sitting, walking, 2 min of gaze stabilization exercise (GSE) coupled with 3 min of trunk mobility exercise (GSE + MOBIL), or 2 min of GSE coupled with a 3-minute walk (GSE + WALK). Baseline and post-activity measurements (rating of perceived discomfort, balance and postural sway measurements, 5-minute psychomotor vigilance task test) were submitted to a paired t-test to determine the effect of WBV exposure and activities on physical, cognitive, and sensorimotor systems and to a repeated measures ANOVA to determine any differences across activities. Results We observed degradation of the slowest 10% reaction speed outcomes between baseline and post-activity after walking (7.3%, p < 0.05) and sitting (8.6%, p < 0.05) but not after GSE + MOBIL or GSE + WALK activities. Slowest 10% reaction speed after GSE + MOBIL activity was faster than all other activities. The rating of perceived discomfort was higher after SIT and WALK activities. There were no notable differences in balance outcomes. Conclusion When compared to sitting for 5 min, an activity including GSE and an active component, such as walking or trunk mobility exercises, resulted in maintenance of reaction time after WBV exposure. If confirmed in occupational environments, GSE may provide a simple, rapid, effective, and inexpensive means to protect against decrements in reaction time after WBV exposure.

Obstructive sleep apnea-related intermittent hypoxaemia is associated with impaired vigilance.

Obstructive sleep apnea (OSA)-related intermittent hypoxaemia is a potential risk factor for different OSA comorbidities, for example cardiovascular disease. However, conflicting results are found as to whether intermittent hypoxaemia is associated with impaired vigilance. Therefore, we aimed to investigate how desaturation characteristics differ between the non-impaired vigilance and impaired vigilance patient groups formed based on psychomotor vigilance task (PVT) performance and compared with traditional OSA severity parameters. The study population comprised 863 patients with suspected OSA who underwent a PVT test before polysomnography. The conventional OSA parameters, for example, the apnea-hypopnea index, oxygen desaturation index, and arousal index were computed. Furthermore, the median desaturation area, fall area, recovery area, and desaturation depth were computed with the pre-event baseline reference and with reference to the 100% oxygen saturation level. Patients were grouped into best- and worst-performing quartiles based on the number of lapses in PVT (Q1: PVT lapses <5 and Q4: PVT lapses >36). The association between parameters and impaired vigilance was evaluated by cumulative distribution functions (CDFs) and binomial logistic regression. Based on the CDFs, patients in Q4 had larger desaturation areas, recovery areas, and deeper desaturations when these were referenced to 100% saturation compared with Q1. The odds ratio (OR) of the median desaturation area (OR=1.56), recovery area (OR=1.71), and depth (OR=1.65) were significantly elevated in Q4 in regression models. However, conventional OSA parameters were not significantly associated with impaired vigilance (ORs: 0.79-1.09). Considering desaturation parameters with a 100% SpO2 reference in the diagnosis of OSA could provide additional information on the severity of OSA and related daytime vigilance impairment.

Effect of Exercise Intensity on Psychomotor Vigilance During an Incremental Endurance Exercise in Under-19 Soccer Players.

The aim of this study was to analyze the acute effects of an incremental resistance test on psychomotor vigilance in 16 soccer players under-19 years old (age 16.42 ± 0.85years). Borg 15-point subjective perception of effort scale, the psychomotor vigilance task test, and the Yo-Yo intermittent recovery test were used. Four evaluation sessions were conducted with different intensities of efforts (30%-40%, 60%-75%, 80%-90%, and 100%) on different days (counterbalanced order). A repeated-measures analysis of variance was performed in the reaction time of the psychomotor vigilance task. The results showed that participants responded faster during efforts between 80% and 90% of maximal oxygen uptake (501.20 ± 70.77ms). From that threshold, the players decreased their performance through a longer reaction time (601.23 ± 85.05ms; p value < .001). The main findings were that the reaction time performance was worse at the lowest and highest effort conditions (5 and 17km/hr, respectively). This fact helps to focus on the importance of designing and proposing training tasks with medium-high efforts to provoke optimal reaction times in young soccer players.

Dose-Response of Paraxanthine on Cognitive Function: A Double Blind, Placebo Controlled, Crossover Trial.

Paraxanthine (PXN) is a metabolite of caffeine that has recently been reported to enhance cognition at a dose of 200 mg. Objective: To determine the acute and short-term (7-day) effects of varying doses of PXN on cognitive function and side effects. Methods: In a double blind, placebo-controlled, crossover, and counterbalanced manner, 12 healthy male and female volunteers (22.7 ± 4 years, 165 ± 7 cm, 66.5 ± 11 kg, 24.4 ± 3 kg/m2) ingested 200 mg of a placebo (PLA), 50 mg of PXN (ENFINITY™, Ingenious Ingredients, L.P.) + 150 mg PLA, 100 mg PXN + 100 mg PLA, or 200 mg of PXN. With each treatment experiment, participants completed side effect questionnaires and donated a fasting blood sample. Participants then performed a series of tests assessing cognition, executive function, memory, and reaction time. Participants then ingested one capsule of PLA or PXN treatments. Participants then completed side effects and cognitive function tests after 1, 2, 3, 4, 5, and 6 h of treatment ingestion. Participants continued ingesting one dose of the assigned treatment daily for 6-days and returned to the lab on day 7 to donate a fasting blood sample, assess side effects, and perform cognitive function tests. Participants repeated the experiment while ingesting remaining treatments in a counterbalanced manner after at least a 7-day washout period until all treatments were assessed. Results: The Sternberg Task Test (STT) 4-Letter Length Present Reaction Time tended to differ among groups (p = 0.06). Assessment of mean changes from baseline with 95% CI’s revealed several significant differences among treatments in Berg-Wisconsin Card Sorting Correct Responses, Preservative Errors (PEBL), and Preservative Errors (PAR Rules). There was also evidence of significant differences among treatments in the Go/No-Go Task tests in Mean Accuracy as well as several time points of increasing complexity among STT variables. Finally, there was evidence from Psychomotor Vigilance Task Test assessment that response time improved over the series of 20 trials assessed as well as during the 6-h experiment in the PXN treatment. Acute and short-term benefits compared to PLA were seen with each dose studied but more consistent effects appeared to be at 100 mg and 200 mg doses. No significant differences were observed among treatments in clinical chemistry panels or the frequency or severity of reported side effects. Results provide evidence that acute ingestion of 100 mg and 200 mg of PXN may affect some measures of cognition, memory, reasoning, and response time as well as help sustain attention. Additionally, that acute and daily ingestion of PXN for 7 days is not associated with any clinically significant side effects. Conclusions: PXN may serve as an effective nootropic agent at doses as low as 50 mg.

Learning Generalized Representations of EEG between Multiple Cognitive Attention Tasks.

Attention can be measured by different types of cognitive tasks, such as Stroop, Eriksen Flanker, and Psychomotor Vigilance Task (PVT). Despite the differing content of the three cognitive tasks, they all require the use of visual attention. To learn the generalized representations from the electroencephalogram (EEG) of different cognitive attention tasks, extensive intra and inter-task attention classification experiments were conducted on three types of attention task data using SVM, EEGNet, and TSception. With cross-validation in intra-task experiments, TSception has significantly higher classification accuracies than other methods, achieving 82.48%, 88.22%, and 87.31% for Stroop, Flanker, and PVT tests respectively. For inter-task experiments, deep learning methods showed superior performance over SVM with most of the accuracy drops not being significant. Our experiments indicate that there is common knowledge that exists across cognitive attention tasks, and deep learning methods can learn generalized representations better.

Effects of Inositol-Enhanced Bonded Arginine Silicate Ingestion on Cognitive and Executive Function in Gamers.

Inositol stabilized arginine silicate (ASI) ingestion has been reported to increase nitric oxide levels while inositol (I) has been reported to enhance neurotransmission. The current study examined whether acute ASI + I (Inositol-enhanced bonded arginine silicate) ingestion affects cognitive function in e-sport gamers. In a double blind, randomized, placebo controlled, and crossover trial, 26 healthy male (n = 18) and female (n = 8) experienced gamers (23 ± 5 years, 171 ± 11 cm, 71.1 ± 14 kg, 20.7 ± 3.5 kg/m2) were randomly assigned to consume 1600 mg of ASI + I (nooLVL®, Nutrition 21) or 1600 mg of a maltodextrin placebo (PLA). Prior to testing, participants recorded their diet, refrained from consuming atypical amounts of stimulants and foods high in arginine and nitrates, and fasted for 8 h. During testing sessions, participants completed stimulant sensitivity questionnaires and performed cognitive function tests (i.e., Berg-Wisconsin Card Sorting task test, Go/No-Go test, Sternberg Task Test, Psychomotor Vigilance Task Test, Cambridge Brain Sciences Reasoning and Concentration test) and a light reaction test. Participants then ingested treatments in a randomized manner. Fifteen minutes following ingestion, participants repeated tests (Pre-Game). Participants then played their favorite video game for 1-h and repeated the battery of tests (Post-Game). Participants observed a 7–14-day washout period and then replicated the study with the alternative treatment. Data were analyzed by General Linear Model (GLM) univariate analyses with repeated measures using weight as a covariate, paired t-tests (not adjusted to weight), and mean changes from baseline with 95% Confidence Intervals (CI). Pairwise comparison revealed that there was a significant improvement in Sternberg Mean Present Reaction Time (ASI + I vs. PLA; p < 0.05). In Post-Game assessments, 4-letter Absent Reaction Time (p < 0.05), 6-letter Present Reaction Time (p < 0.01), 6-letter Absent Reaction Time (p < 0.01), Mean Present Reaction Time (p < 0.02), and Mean Absent Reaction Time (p < 0.03) were improved with ASI + I vs. PLA. There was a non-significant trend in Pre-Game Sternberg 4-letter Present Reaction time in ASI + I vs. PLA (p < 0.07). ASI + I ingestion better maintained changes in Go/No-Go Mean Accuracy and Reaction Time, Psychomotor Vigilance Task Reaction Time, and Cambridge Post-Game Visio-spatial Processing and Planning. Results provide evidence that ASI + I ingestion prior to playing video games may enhance some measures of short-term and working memory, reaction time, reasoning, and concentration in experienced gamers.

Shift rotation, circadian misalignment and excessive body weight influence psychomotor performance: a prospective and observational study under real life conditions

We aimed to evaluate the influence of shift work rotation, circadian misalignment and being overweight/obese on psychomotor performance throughout a complete shift rotation schedule. The study was conducted with 30 males working rotating shifts from a mining company under real life conditions. Individuals were evaluated over seven days in a shift schedule carried out as follow: two shifts in the morning (D1 and D2), two shifts in the afternoon (D3 and D4), 24 hour free day (D5) and two shifts at night (D6 and D7). Work performance was evaluated by psychomotor vigilance task tests (PVT), and actigraphy was used to characterise the rest-activity rhythm based on intradaily variability (IV) and interdaily stability (IS) of nonparametric functions. We found a significant effect of the shift, body mass index (BMI), IS and IV on lapses in attention. More lapses occurred on D7 than D1, D2, D3 and D4 of the schedule shift. The obese group presented a higher number of lapses in attention than eutrophic. The interaction between day and IS showed that less synchronised individuals presented a higher number of lapses in attention on D7 than D1 and, for the interaction between day and IV, more fragmented individuals presented a higher number of lapses in attention on D7 than D6. We conclude that higher BMI, lower synchronisation and higher fragmentation of the rest-activity pattern influenced lapses in attention throughout the shift rotation.

The relationships between improvements in daytime sleepiness, fatigue and depression and psychomotor vigilance task testing with CPAP use in patients with obstructive sleep apnea

ObjectiveThe purpose of this study was to determine if the subjective improvements in daytime sleepiness, fatigue and depression experienced by patients with obstructive sleep apnea (OSA) with continuous positive airway pressure (CPAP) therapy predict an objective improvement in vigilance, and whether patients with mild-to-moderate OSA differ from patients with severe OSA in this regard. MethodsA total of 182 patients underwent psychomotor vigilance task (PVT) testing and measurements of subjective daytime sleepiness, fatigue and depression at baseline and after a minimum of one month of adherent CPAP use at an adequate pressure. ResultsPatients with both mild-to-moderate (n = 92) and severe (n = 90) OSA experienced improvements in subjective daytime sleepiness, fatigue and depression, but objective improvement in vigilance was only seen in patients with severe OSA. In patients with severe OSA, while a correlation was found between improvements in daytime sleepiness and some PVT parameters, changes in subjective daytime sleepiness, fatigue and depression scores were not predictive of objective improvement in vigilance while controlling for all these subjective symptoms and for age, gender, body mass index, apnea-hypopnea index/respiratory event index and total sleep time/total recording time with pulse oximetry below 90%. ConclusionsWe found no predictive relationship between subjective improvements in daytime sleepiness, fatigue and depression and objective vigilance with CPAP use in patients with OSA. These results suggest that subjective complaints of daytime impairment and objective measures of vigilance in patients with OSA should be assessed separately while evaluating the efficacy of CPAP therapy on daytime functioning.

PC-PVT 2.0: An updated platform for psychomotor vigilance task testing, analysis, prediction, and visualization

BackgroundThe psychomotor vigilance task (PVT) has been widely used to assess the effects of sleep deprivation on human neurobehavioral performance. To facilitate research in this field, we previously developed the PC-PVT, a freely available software system analogous to the “gold-standard” PVT-192 that, in addition to allowing for simple visual reaction time (RT) tests, also allows for near real-time PVT analysis, prediction, and visualization in a personal computer (PC). New methodHere we present the PC-PVT 2.0 for Windows 10 operating system, which has the capability to couple PVT tests of a study protocol with the study’s sleep/wake and caffeine schedules, and make real-time individualized predictions of PVT performance for such schedules. We characterized the accuracy and precision of the software in measuring RT, using 44 distinct combinations of PC hardware system configurations. ResultsWe found that 15 system configurations measured RTs with an average delay of less than 10 ms, an error comparable to that of the PVT-192. To achieve such small delays, the system configuration should always use a gaming mouse as the means to respond to visual stimuli. We recommend using a discrete graphical processing unit for desktop PCs and an external monitor for laptop PCs. Comparison with existing methodThis update integrates a study’s sleep/wake and caffeine schedules with the testing software, facilitating testing and outcome visualization, and provides near-real-time individualized PVT predictions for any sleep-loss condition considering caffeine effects. ConclusionsThe software, with its enhanced PVT analysis, visualization, and prediction capabilities, can be freely downloaded from https://pcpvt.bhsai.org.

Performance Male and Female Drivers in Drowsiness System Based on Psychomotor Vigilance Task Test

Driving on the highway that takes a long time and monotonous often causes the motorist or motorcycle to feel fatigue. Fatigue can be divided into two: physical or motoric fatigue and psychological or mental fatigue. As a result of this fatigue the driver may feel drowsiness, loss of concentration that endangers the safety of the driver. Some literature distinguishes gender in ability or driving skills. This paper observed and measured gender differences in driving. Measurements using Psychomotor Vigilance Task to measure mental fatigue before and after the driver were given an Arithmetic Stress Test. The data obtained on experimental drivers of male and female will then be processed using statistical tests to find out whether the psychomotor vigilance task of female and male drivers have same performance or not. Statistical tests were performed using Paired Sample T-Test. We have 17 drivers with 13 men and 4 women, each taken 5 session obtained that the T-test value of session 1 to session 5 have the same result that is the performance male and female drivers has the same performance in fatigue, but the number of male driver collisions smaller than the number of female driver collisions.

0538 CPAP TREATMENT IMPROVES LAPSE COUNT ON PSYCHOMOTOR VIGILANCE TASK TESTING IN PATIENTS WITH OSA: RESULTS OF A PILOT STUDY

Obstructive sleep apnea (OSA) is known to cause sleep fragmentation and hamper daytime performance. While patients with OSA often report a subjective improvement in daytime alertness with continuous airway pressure (CPAP) treatment, it is unclear if such therapy produces an objective increase in daytime vigilance. As part of a larger study, we compared the number of lapses (lack of response to visual stimulation for 500 msecs or longer) during psychomotor vigilance task (PVT) testing in patients with OSA before and after CPAP therapy to determine whether there was improvement in vigilance. Sixty-nine adult patients (72.5% male; mean age 49.9 years, SD ±12.3) determined to have OSA by virtue of an apnea-hypopnea index [AHI] >5/hr on their diagnostic sleep study (mean AHI 41.9/hr, SD ±37.1) performed a ten-minute PVT test before and after adequate use of CPAP for a minimum of one month. Adequate CPAP use was defined as compliance of more than 4 hours per night for a minimum of 70% of nights, averaged over the preceding 30 days, and with an average residual AHI of <5/hr during that time period. The number of lapses before and after CPAP treatment was recorded and compared. A paired t-test was used to look for a significant difference in the mean number of lapses. There was a small but significant improvement in the mean number of lapses on PVT testing (1.9 post-treatment vs. 2.9 pre-treatment) in patients with OSA treated adequately with CPAP for at least a month (p=0.03). Our pilot data suggest that treatment with CPAP improves daytime vigilance in patients with OSA. This has important implications in the management of patients with OSA, particularly those in whom sustained concentration is an essential employment skill, such as commercial drivers. Larger studies that explore the best predictors of improvement in PVT performance with CPAP treatment in patients with OSA are awaited. N/A.

Evaluation of a Psychomotor Vigilance Task for Touch Screen Devices.

Our goals were to compare three techniques for performing a psychomotor vigilance task (PVT) on a touch screen device (fifth-generation iPod) and to determine the device latency. The PVT is a reaction-time test that is sensitive to sleep loss and circadian misalignment. Several PVT tests have been developed for touch screen devices, but unlike the standard PVT developed for laboratory use, these tests allow for touch responses to be recorded at any location on the device, with contact from any finger. In addition, touch screen devices exhibit latency in processing time between the touch response and the time registered by the device. Thirteen participants completed a 5-min PVT on a touch screen device held in three positions (on a table with index finger, handheld portrait with index finger, handheld landscape with thumb). We compared reaction-time outcomes in each orientation condition using paired t tests. We recorded the first session using a high-speed video camera to determine the latency between the touch response and the documented response time. The participants had significantly faster reaction times in the landscape-oriented position using the thumb, compared with the portrait-oriented position using the index ( M = 224.13 and M = 244.26, p = .045). Using data from 1,241 unique touch events, we found a mean device latency of 68.53 ms that varied highly between individuals. Device orientation and device latency should be considered when using a touch screen version of a PVT. Our findings apply to researchers administering touch screen versions of the PVT.

Driving Performance of Residents after Six Consecutive Overnight Work Shifts.

Residency training requires work in clinical settings for extended periods of time, resulting in altered sleep patterns, sleep deprivation, and potentially deleterious effects on safe performance of daily activities, including driving a motor vehicle. Twenty-nine anesthesiology resident physicians in postgraduate year 2 to 4 drove for 55 min in the Virginia Driving Safety Laboratory using the Driver Guidance System (MBFARR, LLC, USA). Two driving simulator sessions were conducted, one experimental session immediately after the final shift of six consecutive night shifts and one control session at the beginning of a normal day shift (not after call). Both sessions were conducted at 8:00 AM. Psychomotor vigilance task testing was employed to evaluate reaction time and lapses in attention. After six consecutive night shifts, residents experienced significantly impaired control of all the driving variables including speed, lane position, throttle, and steering. They were also more likely to be involved in collisions. After six consecutive night shifts, residents had a significant increase in reaction times (281.1 vs. 298.5 ms; P = 0.001) and had a significant increase in the number of both minor (0.85 vs. 1.88; P = 0.01) and major lapses (0.00 vs. 0.31; P = 0.008) in attention. Resident physicians have greater difficulty controlling speed and driving performance in the driving simulator after six consecutive night shifts. Reaction times are also increased with emphasis on increases in minor and major lapses in attention after six consecutive night shifts.

Daytime sleepiness associated with poor sustained attention in middle and late adulthood

ObjectiveWe aimed to determine the association between psychomotor vigilance task (PVT) performance and sleep-related factors including sleep duration, daytime sleepiness, poor sleep quality, insomnia, and habitual snoring in a population-based sample. MethodsThis was a cross-sectional analysis from the ongoing prospective cohort study, the Korean Genome and Epidemiology Study. We measured PVT performance and documented demographics, sleep-related factors, life style, and medical conditions in community dwelling adults (N = 2499; mean age 57.1 ± 7.3; male 1259). Associations between PVT parameters and sleep-related factors were tested, adjusting for age, gender, smoking, alcohol use, education, body mass index, hypertension, diabetes, depression, and the interval between mid-sleep time and PVT test. ResultsHigh Epworth Sleepiness Scale (ESS, ≥8) was associated with slower mean reciprocal response speed (mean RRT) (3.69 ± 0.02 vs. 3.77 ± 0.01, p < 0.001), higher probability for increased lapses (≥4) (OR 1.48, CI 1.12–1.88, p = 0.001), and more negative RRT slope (−0.036 ± 0.002 vs. −0.030 ± 0.001, p = 0.02). Older age, female gender, low education level, depressive mood, and the interval between mid-sleep and PVT test were also associated with poor performance. Sleep duration, habitual snoring, insomnia, or poor sleep quality (the Pittsburgh Sleep Quality Index score > 5) was not related to PVT parameters. ConclusionsAt the population level, our results revealed important modifiers of PVT performance, which included subjective reports of daytime sleepiness.

Napping on the Night Shift: A Study of Sleep, Performance, and Learning in Physicians-in-Training

Physicians in training experience fatigue from sleep loss, high workload, and working at an adverse phase of the circadian rhythm, which collectively degrades task performance and the ability to learn and remember. To minimize fatigue and sustain performance, learning, and memory, humans generally need 7 to 8hours of sleep in every 24-hour period. In a naturalistic, within-subjects design, we studied 17 first- and second-year internal medicine residents working in a tertiary care medical center, rotating between day shift and night float every 4weeks. We studied each resident for 2weeks while he/she worked the day shift and for 2weeks while he/she worked the night float, objectively measuring sleep by wrist actigraphy, vigilance by the Psychomotor Vigilance Task test, and visual-spatial and verbal learning and memory by the Brief Visuospatial Memory Test-Revised and the Rey Auditory-Verbal Learning Test. Residents, whether working day shift or night float, slept approximately 7hours in every 24-hour period. Residents, when working day shift, consolidated their sleep into 1 main sleep period at night. Residents working night float split their sleep, supplementing their truncated daytime sleep with nighttime on-duty naps. There was no difference in vigilance or learning and memory, whether residents worked day shift or night float. Off-duty sleep supplemented with naps while on duty appears to be an effective strategy for sustaining vigilance, learning, and memory when working night float.

Behavioural evidence that modafinil and amphetamine do not produce equivalent qualities of wake promotion in sleep-restricted rats

Introduction Performance effects of sleep restriction are generally assessed across three broad domains: cognitive performance, motor performance and mood. Within the domain of cognition, the psychomotor vigilance task (PVT) provides a means to assess vigilant attentional capacity with low cognitive demand, allowing robust deficits following sleep restriction. Using rats, we directly compared equipotent doses of modafinil with amphetamine (in terms of their EEG wake-promoting effects) to access their capacity to reverse attention deficits following 11hrs of sleep restriction. Materials and methods During the PVT task, Reaction Time (RT) latencies are measured to the onset of an imperative light cue that signals food reward, occurring under a variable interval 5s schedule following a houselight preparatory cue. Previous in house studies have demonstrated marked behavioural deficits following 11 h automated biofeedback sleep restriction, where both median RTs slowed and omissions increased. Results Using PVT testing following such a sleep restriction protocol modafinil reversed the effects of sleep restriction with regard to trials completed and omissions. However, there was a pronounced increase in premature responding at the highest dose tested. Administration of amphetamine worsened the behavioural effects of sleep restriction, decreasing trials and increasing response omissions and median response latencies. Both modafinil and amphetamine produced similar wake-promoting effects with regard to EEG measurements. Conclusion In conclusion, these studies demonstrate that simple reaction time measures following sleep restriction can preclinically determine functional differences in wake-promoting compounds that would otherwise remain undetectable using EEG measurements alone. Acknowledgement I’d like to acknowledge Christopher Baxter for his technical involvement in this work.

Circadian adaptation of airline pilots during extended duration operations between the USA and Asia

This study tracked circadian adaptation among airline pilots before, during, and after trips where they flew from Seattle (SEA) or Los Angeles (LAX) to Asia (7--9 time zones westward), spent 7--12 d in Asia, and then flew back to the USA. In Asia, pilots' exposures to local time cues and sleep opportunities were constrained by duty (short-haul flights crossing ≤1 time zone/24 h). Fourteen captains and 16 first officers participated (median age = 56 versus 48 yrs, p.U) < 0.001). Their sleep was monitored (actigraphy, duty/sleep diaries) from 3 d pre-trip to 5 d post-trip. For every flight, Karolinska Sleepiness and Samn-Perelli Fatigue scales and 5-min psychomotor vigilance task (PVT) tests were completed pre-flight and at top of descent (TOD). Participants had ≥3 d free of duty prior to outbound flight(s). From 72--24 h prior to departure (baseline sleep), mean total sleep/24 h (TST) = 7.00 h (SD = 1.18 h) and mean sleep efficiency = 87% (SD = 4.9%). Most pilots (23/30) flew direct to and from Asia, but 7 LAX-based pilots flew via a 1-d layover in Honolulu (HNL). On flights with ≥2 pilots, mean total in-flight sleep varied from 0.40 to 2.09 h outbound and from 0.74 to 1.88 h inbound. Duty patterns in Asia were variable, with ≤2 flights/d (mean flight duration = 3.53 h, SD = 0.53 h). TST on days 17 in Asia did not differ from baseline (p.F) = 0.2031). However, mean sleep efficiency was significantly lower than baseline on days 5--7 (p.F) = 0.0041). More pilots were on duty between 20:00 and 24:00 h on days 57 (mean = 21%) than on days 24 (mean = 14%). Sleep propensity distribution phase markers and chi-square periodogram analyses suggest that adaptation to local time was complete by day 4 in Asia. On pre-flight PVT tests in Asia, the slowest 10% of responses improved for flights departing 14:00--19:59 h (p.F) = 0.0484). At TOD, the slowest 10% of responses improved across days for flights arriving 14:00--19:59 h (p.F) = 0.0349) and 20:00--01:59 h (p.F) = 0.0379). Sleepiness and fatigue ratings pre-flight and at TOD did not change across days in Asia. TST on post-trip day 1 was longer than baseline (estimated mean extension = 1.68 h; adjusted p(t) < 0.0001). On all post-trip days, sleep efficiency was comparable to baseline. Sleep propensity distribution phase markers and chi-square periodogram analyses suggest complete readaptation in 12 d. Two opposing influences appeared to affect sleep and PVT performance across days in Asia: progressive circadian adaptation to local time and increasing duty during local night, which displaced sleep from the optimal physiological time. Cumulative sleep restriction across the return flight may explain the large rebound in TST on day 1 post-trip. Thereafter TST, sleep efficiency, and sleep timing suggest that readaptation was complete. Rapid post-trip readaptation may be facilitated by pilots having unconstrained nocturnal sleep opportunities, coupled with stronger patterns of family and social cues than in Asia.