Psychomotor Vigilance Task Performance Research Articles

Increased flow limitation during sleep is associated with decreased psychomotor vigilance task performance in individuals with suspected obstructive sleep apnea: a multi-cohort study.

Increased flow limitation during sleep is associated with decreased psychomotor vigilance task performance in individuals with suspected obstructive sleep apnea: a multi-cohort study.

Effects of total sleep deprivation on performance in a manual spacecraft docking task

Sleep deprivation and circadian rhythm disruptions are highly prevalent in shift workers, and also among astronauts. Resulting sleepiness can reduce cognitive performance, lead to catastrophic occupational events, and jeopardize space missions. We investigated whether 24 hours of total sleep deprivation would affect performance not only in the Psychomotor Vigilance Task (PVT), but also in a complex operational task, i.e. simulated manual spacecraft docking. Sixty-two healthy participants completed the manual docking simulation 6df and the PVT once after a night of total sleep deprivation and once after eight hours of scheduled sleep in a counterbalanced order. We assessed the impact of sleep deprivation on docking as well as PVT performance and investigated if sustained attention is an essential component of operational performance after sleep loss. The results showed that docking accuracy decreased significantly after sleep deprivation in comparison to the control condition, but only at difficult task levels. PVT performance deteriorated under sleep deprivation. Participants with larger impairments in PVT response speed after sleep deprivation also showed larger impairments in docking accuracy. In conclusion, sleep deprivation led to impaired 6df performance, which was partly explained by impairments in sustained attention. Elevated motivation levels due to the novelty and attractiveness of the task may have helped participants to compensate for the effects of sleepiness at easier task levels. Continued testing of manual docking skills could be a useful tool both to detect sleep loss-related impairments and assess astronauts’ readiness for duty during long-duration missions.

Impact on health outcomes associated with changing the clock one hour during fall and spring transitions in the Southern American Hemisphere.

Changing the clocks seasonally is potentially harmful because it interferes with normal daytime activities. Studies aimed at quantifying this association are scant. The objective of this study was to determine the effects of one year's worth of changing the clocks (fall and spring transitions) on healthy young men located in the Southern American Hemisphere. We performed an observational prospective study. Thirty healthy male university students were evaluated from two weeks before to two weeks after both the fall and spring transitions. We administered an overall sleep questionnaire, assessed quality of life, recorded 7-day wrist actigraphy, and had participants perform a Psychomotor Vigilance Task (PVT). We defined the one-hour clock change as the primary exposure and the change in PVT lapses of 500 ms or more in response time as our primary outcome. Changes were evaluated by the Wilcoxon rank test (significance: P<0.05). After the fall transition, we found a significant worsening in PVT performance (median [IQR] 9.9 [6.0-14.3] lapses of ≥ 500 ms in response time at baseline vs 16.8 [8.2-28.0] after transition; P<0.002). Additionally, we found a median loss of about one hour of total sleep time and time in bed after the fall transition. Furthermore, participants presented with insomnia. PVT performance was also affected after the spring transition (16.7 [10-23] vs 23 [12.2-32.2]; P<0.001). A decrease in performance in neurocognitive tests was found after both time transitions. The transition led to insomnia and a significant worsening of sleep variables.

Cognitive performance of air personnel following sleep deprivation.

Air forces have developed several methods for reducing fatigue-related accidents. In the Israeli Air Force, the "Dead Tired" workshop was developed with the purpose of presenting aircrew with their objective performance under sleep deprivation conditions. The aim of this study was to examine the cognitive abilities of both aircrew and unmanned aerial vehicle operators, both objectively and subjectively. All Israeli aircrew and unmanned aerial vehicle operators participated in a "Dead Tired" workshop. During the workshop, the participants performed the Psychomotor Vigilance Task, a task that tests their attention abilities, while gathering information on their subjective sleepiness in the form of a Karolinska Sleepiness Scale. Data of 366 participants (25 females), of whom 187 were unmanned aerial vehicle operators and 179 were aircrew, were obtained; and the mean age was 21.8 ± 1.2 years (range 19-26 years). A significant decline in task performance was seen following 20 hr of wakefulness in both unmanned aerial vehicle operators and aircrew (p < 0.001). Unmanned aerial vehicle operators' performance was significantly better throughout the majority of the workshop (p < 0.001). Recovery after the full-night's sleep was seen for unmanned aerial vehicle operators, but not for aircrew (p = 0.008). A high correlation was seen between Psychomotor Vigilance Task performance and Karolinska Sleepiness Scale responses (correlation coefficient = 0.93). Sleep deprivation negatively impacted the performance of both groups of participants. Unmanned aerial vehicle operators were found to be more resilient to the effects of sleep deprivation and were quicker to recover in comparison to aircrew.

Estimating vigilance from the pre-work shift sleep using an under-mattress sleep sensor.

Predicting vigilance impairment in high-risk shift work occupations is critical to help to reduce workplace errors and accidents. Current methods rely on multi-night, often manually entered, sleep data. This study developed a machine learning model for predicting vigilance errors based on a single prior sleep period, derived from an under-mattress sensor. Twenty-four healthy volunteers (mean [SD] age = 27.6 [9.5] years, 12 male) attended the laboratory on two separate occasions, 1 month apart, to compare wake performance and sleep under two different lighting conditions. Each condition occurred over an 8 day protocol comprising a baseline sleep opportunity from 10 p.m. to 7 a.m., a 27 h wake period, then daytime sleep opportunities from 10 a.m. to 7 p.m. on days 3-7. From 12 a.m. to 8 a.m. on each of days 4-7, participants completed simulated night shifts that included six 10 min psychomotor vigilance task (PVT) trials per shift. Sleep was assessed using an under-mattress sensor. Using extra-trees machine learning models, PVT performance (reaction times <500 ms, reaction, and lapses) during each night shift was predicted based on the preceding daytime sleep. The final extra-trees model demonstrated moderate accuracy for predicting PVT performance, with standard errors (RMSE) of 19.9 ms (reaction time, 359 [41.6]ms), 0.42 reactions/s (reaction speed, 2.5 [0.6] reactions/s), and 7.2 (lapses, 10.5 [12.3]). The model also correctly classified 84% of trials containing ≥5 lapses (Matthews correlation coefficient = 0.59, F1 = 0.83). Model performance is comparable to current fatigue prediction models that rely upon self-report or manually entered data. This efficient approach may help to manage fatigue and safety in non-standard work schedules.

The role of the fronto-parietal network in modulating sustained attention under sleep deprivation: an functional magnetic resonance imaging study.

The intricate relationship between sleep deprivation (SD) and cognitive performance has long been a subject of research. Our study offers a novel angle by closely examining the neurobiological underpinnings of sustained attention deficits through the lens of the fronto-parietal network (FPN). Using state-of-the-art imaging techniques, we delve into the changes in spontaneous brain activity after SD and explore their associations with performance on the psychomotor vigilance task (PVT). We conducted an elaborate investigation involving 64 healthy, right-handed participants who underwent resting-state functional MRI scans before and after experiencing 24 h of sleep deprivation. Employing sophisticated statistical analyses, we scrutinized the changes in fractional amplitude of low-frequency fluctuations (fALFF) through paired t-tests. Pearson correlation analyses were then applied to dissect the associations between these neurobiological shifts and behavioral outcomes in PVT. The study yielded remarkable findings, revealing a dramatic decrease in fALFF values within critical areas of the FPN following SD. These alterations predominantly occurred in the frontal and parietal gyri and were inversely correlated with PVT performance metrics. Furthermore, we discovered that baseline fALFF values in the left dorsolateral prefrontal cortex (DLPFC) have the potential to serve as compelling neurobiological markers, with high discriminatory power in identifying individual responses to the adverse effects of SD on cognitive performance. Our groundbreaking research underscores the pivotal role that the FPN plays in modulating attention and executive function, especially under the challenging conditions brought about by sleep deprivation. The findings offer critical insights that could shape the way we understand, assess, and potentially mitigate the cognitive impacts of SD, setting the stage for future research in this riveting domain.

Structural abnormalities in the Fronto-Parietal Network: Linking white matter integrity to sustained attention deficits in Schizophrenia

Schizophrenia is associated with a range of cognitive deficits, among which impairments in sustained attention are particularly significant. Previous research has investigated functional changes in the fronto-parietal network (FPN) related to attentional control in schizophrenia. However, the role of structural connectivity within the FPN in sustained attention deficits remains under-explored. Utilizing diffusion tensor imaging (DTI), this study investigated white matter integrity in 75 participants, comprising 37 individuals with schizophrenia (SZ) and 38 healthy controls (HC). Psychomotor vigilance task (PVT) performance was assessed to gauge sustained attention. The SZ group showed a significant reduction in fractional anisotropy (FA) and streamline counts within white matter tracts connecting frontal and parietal regions, compared to the HC group. Further, significant negative correlations were found between PVT performance and white matter integrity measures within the SZ group, specifically in the left FPN. Our findings indicate that structural abnormalities in the FPN are associated with sustained attention deficits in schizophrenia. These results contribute to our understanding of the neurobiological mechanisms underlying cognitive impairments in schizophrenia and offer potential avenues for targeted therapeutic interventions. Further research is warranted to validate these outcomes and explore their clinical implications.

A pilot study of light exposure as a countermeasure for menstrual phase-dependent neurobehavioral performance impairment in women

ObjectiveTo examine effects of menstrual phase and nighttime light exposure on subjective sleepiness and auditory Psychomotor Vigilance Task performance. MethodsTwenty-nine premenopausal women (12 =Follicular; 17 =Luteal) completed a 6.5-hour nighttime monochromatic light exposure with varying wavelengths (420-620 nm) and irradiances (1.03-14.12 µW/cm2). Subjective sleepiness, reaction time, and attentional lapses were compared between menstrual phases in women with minimal (<33%) or substantial (≥33%) light-induced melatonin suppression. ResultsWhen melatonin was not suppressed, women in the follicular phase had significantly worse reaction time (mean difference=145.1 ms, 95% CI 51.8-238.3, p < .001, Cohen’s D=1.9) and lapses (mean difference=12.9 lapses, 95% CI 4.37-21.41, p < .001, Cohen’s D=1.7) compared to women in the luteal phase. When melatonin was suppressed, women in the follicular phase had significantly better reaction time (mean difference=152.1 ms, 95% CI 43.88-260.3, p < .001, Cohen’s D=1.7) and lapses (mean difference=12.3 lapses, 95% CI 1.14-25.6, p < .01, Cohen’s D=1.6) compared to when melatonin was not suppressed, such that their performance was not different (p > .9) from women in the luteal phase. Subjective sleepiness did not differ by menstrual phase (mean difference=0.6, p > .08) or melatonin suppression (mean difference=0.2, p > .4). ConclusionsNighttime light exposure sufficient to suppress melatonin can also mitigate neurobehavioral performance deficits associated with the follicular phase. Despite the relatively small sample size, these data suggest that nighttime light may be a valuable strategy to help reduce errors and accidents in female shift workers.

How much can we improve two-section watch bills? Sleepiness, Fatigue, and Psychomoter Vigilance Performance during naval operations in the 6/6 and 7-5-5-7 watch bills

A traditional two-section watch bill (6 hours on / 6 hours off, starting at midnight – “6/6”) and a two-section watch bill better adapted to the human circadian rhythm (watches of 7, 5, 5, and 7 hours duration, starting at 3 a.m. – “7-5-5-7”) were trialed on two vessels of the German Navy with 67 study participants in a crossover design. Questionnaires were used to assess subjective sleepiness (ESS, KSS) and subjective fatigue (FSS). The psychomotor vigilance task (PVT) was self-administered with wearable devices before and after each watch. Over the course of seven days at sea, PVT performance worsened significantly with the 6/6, but not with the 7-5-5-7 watch bill. In the 6/6 watch bill, number of participants with excessive sleepiness and high levels of fatigue was higher than in the 7-5-5-7 watch bill although not at a statistically significant level. Marked differences between watch bills in crew performance started to emerge after 6 days.

White matter structural topologic efficiency predicts individual resistance to sleep deprivation.

Sleep deprivation (SD) is commonplace in modern society and there are large individual differences in the vulnerability to SD. We aim to identify the structural network differences based on diffusion tensor imaging (DTI) that contribute to the individual different vulnerability to SD. The number of psychomotor vigilance task (PVT) lapses was used to classify 49 healthy subjects on the basis of whether they were vulnerable or resistant to SD. DTI and graph theory approaches were used to investigate the topologic organization differences of the brain structural connectome between SD-vulnerable and -resistant individuals. We measured the level of global efficiency and clustering in rich club and non-rich club organizations. We demonstrated that participants vulnerable to SD had less global efficiency, network strength, and local efficiency but longer shortest path length compared with participants resistant to SD. Lower efficiency was mainly distributed in the right insula, bilateral thalamus, bilateral frontal, temporal, and temporal lobes. Furthermore, a disrupted subnetwork was observed that consisted of widespread connections. Moreover, the vulnerable group showed significantly decreased strength of the rich club compared with the resistant group. The strength of rich club connectivity was found to be correlated negatively with PVT performance (r = -0.395, p = 0.005). We further tested the reliability of the results. The findings revealed that individual differences in resistance to SD are related to disrupted topologic efficiency connectome pattern, and our study may provide potential connectome-based biomarkers for the early detection of the vulnerable degree to SD.

Physiological synchrony in electrodermal activity predicts decreased vigilant attention induced by sleep deprivation.

When multiple individuals are presented with narrative movie or audio clips, their electrodermal activity (EDA) and heart rate show significant similarities. Higher levels of such inter-subject physiological synchrony are related with higher levels of attention toward the narrative, as for instance expressed by more correctly answered questions about the narrative. We here investigate whether physiological synchrony in EDA and heart rate during watching of movie clips predicts performance on a subsequent vigilant attention task among participants exposed to a night of total sleep deprivation. We recorded EDA and heart rate of 54 participants during a night of total sleep deprivation. Every hour from 22:00 to 07:00 participants watched a 10-min movie clip during which we computed inter-subject physiological synchrony. Afterwards, they answered questions about the movie and performed the psychomotor vigilance task (PVT) to capture attentional performance. We replicated findings that inter-subject correlations in EDA and heart rate predicted the number of correct answers on questions about the movie clips. Furthermore, we found that inter-subject correlations in EDA, but not in heart rate, predicted PVT performance. Individuals' mean EDA and heart rate also predicted their PVT performance. For EDA, inter-subject correlations explained more variance of PVT performance than individuals' mean EDA. Together, these findings confirm the association between physiological synchrony and attention. Physiological synchrony in EDA does not only capture the attentional processing during the time that it is determined, but also proves valuable for capturing more general changes in the attentional state of monitored individuals.

Hybrid effectiveness-implementation study of two novel spectrally engineered lighting interventions for shiftworkers on a high-security watchfloor

Abstract Shiftwork leads to myriad negative health and safety outcomes. Lighting countermeasures can benefit shiftworkers via physiological effects of light (e.g. alerting, circadian adjustment), and short-wavelength light is the most potent for eliciting those responses; however, limited work indicates it may not be required for alerting. We developed similar-appearing light boxes (correlated color temperature: 3000–3375 K; photopic illuminance: 260–296 lux), enriched (SW+, melanopic EDI: 294 lux) or attenuated (SW-, melanopic EDI: 103 lux) in short-wavelength energy, and implemented them on a high-security watchfloor. Efficacy and feasibility of these two novel lighting interventions were assessed in personnel working 12-hour night shifts (n = 47) in this within-participants, crossover study. For each intervention condition, light boxes were arranged across the front of the watchfloor and illuminated the entire shift; blue-blocking glasses were worn post-shift and before sleep; and sleep masks were used while sleeping. Comparisons between baseline and intervention conditions included alertness, sleep, mood, quality of life (QOL), and implementation measures. On-shift alertness (Karolinska Sleepiness Scale) increased in SW- compared to baseline, while changes in SW+ were more limited. Under SW+, both mood and sleep improved. Psychomotor vigilance task performance did not vary by condition; however, perceived performance and QOL were higher, and reported caffeine consumption and sleep onset latency were lower, under SW-. For both interventions, satisfaction and comfort were high, and fewer symptoms and negative feelings were reported. The addition of spectrally engineered lights to this unique work environment improved sleep, alertness, and mood without compromising visual comfort and satisfaction. This paper is part of the Sleep and Circadian Rhythms: Management of Fatigue in Occupational Settings Collection.

Transcutaneous auricular vagus stimulation (taVNS) improves human working memory performance under sleep deprivation stress

Many human activities require high cognitive performance over long periods, while impairments induced by sleep deprivation influence various aspects of cognitive abilities, including working memory (WM), attention, and processing speed. Based on previous research, vagal nerve stimulation can modulate cognitive abilities, attention, and arousal. Two experiments were conducted to assess the efficacy of transcutaneous auricular vagus nerve stimulation (taVNS) to relieve the deleterious effects of sleep deprivation. In the first experiment, 35 participants completed N-back tasks at 8:00 a.m. for two consecutive days in a within-subject study. Then, the participants received either taVNS or earlobe stimulation (active control) intervention in two sessions at random orders after 24 h of sustained wakefulness. Then, they completed the N-back tasks again. In the second experiment, 30 participants completed the psychomotor vigilance task (PVT), and 32 completed the N-back tasks at 8:00 a.m. on the first and second days. Then, they received either taVNS or earlobe stimulation at random orders and finished the N-back and PVT tasks immediately after one hour. In Experiment 1, taVNS could significantly improve the accuracy rate of participants in spatial 3-back tasks compared to active control, which was consistent with experiment 2. However, taVNS did not specifically enhance PVT performance. Therefore, taVNS could be a powerful intervention for acute sleep deprivation as it can improve performance on high cognitive load tasks and is easy to administer.

Desaturation event scoring criteria affect the perceived severity of nocturnal hypoxic load

Objectives/BackgroundInterest in using blood oxygen desaturations in the diagnostics of sleep apnea has risen in recent years. However, no standardized criteria for desaturation scoring exist which complicates the drawing of solid conclusions from literature. Patients/methodsWe investigated how different desaturation scoring criteria affect the severity of nocturnal hypoxic load and the prediction of impaired daytime vigilance in 845 patients. Desaturations were scored based on three features: 1) minimum oxygen saturation drop during the event (2–20%, 1% interval), 2) minimum duration of the event (2–20s, 1s interval), and 3) maximum plateau duration within the event (5–60s, 5s interval), resulting in 4332 different scoring criteria. The hypoxic load was described with oxygen desaturation index (ODI), desaturation severity (DesSev), and desaturation duration (DesDur) parameters. Association between hypoxic load and impaired vigilance was investigated with covariate-adjusted area under curve (AUC) analyses by dividing patients into normal (≤5 lapses) and impaired (≥36 lapses) vigilance groups based on psychomotor vigilance task performance. ResultsThe severity of hypoxic load varied greatly between different scoring criteria. For example, median ODI ranged between 0.4 and 12.9 events/h, DesSev 0.01–0.23 %-point, and DesDur 0.3–9.6 %-point when the minimum transient drop criterion of 3% was used and other two features were altered. Overall, the minimum transient drop criterion had the largest effect on parameter values. All models with differently determined parameters predicted impaired vigilance moderately (AUC = 0.722–0.734). ConclusionsDesaturation scoring criteria greatly affected the severity of hypoxic load. However, the difference in the prediction of impaired vigilance between different criteria was rather small.

0637 Associations between Alzheimer’s Disease Pathology and the Psychomotor Vigilance Task in Cognitively Unimpaired Adults with and without Obstructive Sleep Apnea

Abstract Introduction Daytime sleepiness is a risk factor for Alzheimer’s disease (AD) pathology and is associated with more severe cardiometabolic sequalae in persons with obstructive sleep apnea (OSA). However, limited studies have examined objective measures of decreased alertness in the context of AD. Here, we examined performance on the psychomotor vigilance task (PVT) in relation to AD pathology as indexed by AD biomarkers in cerebrospinal fluid (CSF), among individuals with and without OSA. Methods Sixty-one cognitively unimpaired adults (39 women), mean age 66.1±7.5 years, enrolled in the Wisconsin Alzheimer’s Disease Research Center completed a multifaceted sleep assessment. WatchPAT at-home overnight recordings characterized OSA severity, defined by the apnea-hypopnea index (AHI). Actigraphy determined habitual sleep-wake characteristics. 10-minute PVT measured neurobehavioral alertness. CSF biomarkers were measured using the Roche NeuroToolKit assays (Roche Diagnostics International Ltd, Rotkreuz, Switzerland), an exploratory panel of immunoassays for neurodegeneration. Generalized linear models examined associations between AD biomarkers, AHI, and PVT performance. Primary AD biomarkers of interest were phosphorylated-tau (p-tau) and amyloid-beta (Ab) 42/40 ratio, measured in CSF. The primary PVT variable of interest was the mean response time of the 10% slowest responses, which is associated with daytime sleepiness and default mode network activity. Log transformed PVT and AHI+1 were utilized for analysis. Covariates included age, sex, body mass index, total sleep time, sleep efficiency, APOEe4 status, years of education, AD parental history, biomarker-to-sleep assessment time interval, and Ab42/40 (for p-tau). Results No significant relationship of AHI or PVT was observed for Ab42/40. In fully adjusted models, a significant AHI*PVT interaction was observed for p-tau (p=0.0003). Specifically, among individuals with OSA (AHI&amp;gt;5/hour; n=24), slower PVT was associated with increased p-tau (b=13.2, p=0.006), an association that was not significant among those without OSA. Conclusion PVT performance may be an objective measure of sleepiness relevant to AD pathology, particularly among individuals with OSA. Replication and expansion of these findings in larger and longitudinal datasets are indicated. Support (If Any) R03AG063274 and P30-AG062715.

0097 REM-like Neural Activity Is Superior to NREM Parameters for Predicting Non-sleep Restricted Vigilance

Abstract Introduction Currently unknown is whether REM-like neural activity reverses, incurs, or is neutral with respect to its effect on sleep pressure independent from NREM recovery. We investigated the relationship between a novel scalp-EEG measure of REM-like neural activity and next-day performance on the Psychomotor Vigilance Task (PVT) – a sensitive measure of sleep debt. Our EEG measure reflects the oscillatory-theta activity (OTA) that is the hallmark of REM sleep in animal studies. This method preserves amplitude information, isolates OTA from aperiodic theta-band power, and accounts for REM-like activity thought to occur outside of conventionally scored-REM epochs. We compared the PVT-association of OTA, traditionally measured EEG REM-theta, and traditional sleep parameters. To assess REM-like independent effects, we controlled for traditional parameters using a multivariate model. Methods Our method uses Irregular-Resampling Auto-Spectral Analysis to remove the aperiodic spectrum, followed by low-band power normalization to derive the relative oscillatory-theta activity (OTA). The average OTA was then used to predict next-day performance on the PVT. Traditional sleep parameters (sleep efficiency, total sleep time, %NREM, %N3, and delta-band power) were also examined. We combined data from two previously reported in-laboratory studies resulting in a sample size of 42 healthy young adult subjects. Analyses used non-sleep restricted overnight EEG recordings from a frontal channel. Results There was a substantial PVT-OTA association (OTA positively correlated with response-time and thus with reduced vigilance) during scored-REM epochs (r=0.44, p=0.003). This was stable irrespective of conventional sleep staging when using all sleep epochs (r=0.48, p=0.001), and OTA during scored-NREM (r=0.35, p=0.02). The effect was also stable after controlling for total sleep time, %NREM, and N3 delta-band power in a multivariate model (all-sleep PVT-OTA: r=0.5, p=0.004). Traditional sleep parameters were not significantly correlated with PVT performance. Conclusion OTA was a superior quantitative predictor of reduced next-day vigilance than traditional sleep parameters, and this persisted after controlling for NREM parameters. These findings are consistent with the hypothesis that periods of high REM-like activity are less restorative than other periods and may actually increase homeostatic sleep pressure. Support (If Any) This effort was supported by the Department of Defense Military Operational Medicine Research Program.

Multi-Attribute Task Battery configuration to effectively assess pilot performance deterioration during prolonged wakefulness

Multi-Attribute Task Battery (MATB) simulates realistic and complex aviation-related tasks a pilot routinely performs during flight. However, past studies using MATB have been unable to consistently elicit the effects of performance degradation during prolonged wakefulness. We surmise that this is because the task difficulty level of the MATB software was set too low. The MATB test that was designed for this protocol includes four tasks: system monitoring (SYSMON), communication (COMM), resource management (RESMAN), and all three tasks performed simultaneously. Twenty subjects performed a “session” consisting of both the psychomotor vigilance task (PVT) and the MATB test every 2 h over 25 h of prolonged wakefulness (i.e., for thirteen sessions). The difficulty levels were set to low for both SYSMON and COMM tasks, medium for RESMAN, and high for completion of the three tasks simultaneously, based on NASA task load index. We then calculated the correlation between PVT and MATB indices. As in previous studies, all PVT performance measures were significantly degraded in the last 2–4 sessions of the task, relative to sessions earlier in the 25-hr period. MATB indices were highly correlated with PVT indices. Moreover, all MATB tasks showed significant performance degradation during prolonged wakefulness unlike previous studies. Finally, the considerably more difficult multitasking required by the three simultaneous tasks led to a more consistent and higher degree of performance degradation with prolonged wakefulness than did most of the single tasks, which were set to either low or medium difficulty level. Thus, our results support the hypothesis that previous work failed to show significant performance degradation with prolonged wakefulness during the MATB due to inadequate levels of task difficulty. Our results provide evidence that the MATB, if set to an appropriate level of difficulty, can be used as an alternative to the PVT to more accurately study the effects of prolonged wakefulness on performance of realistic aviation tasks.

Associations between obstructive sleep apnea, Alzheimer’s disease pathology, and objective daytime sleepiness measured by the psychomotor vigilance task in cognitively unimpaired adults

AbstractBackgroundDaytime sleepiness is common among individuals with obstructive sleep apnea (OSA), and has been reported among individuals with Alzheimer’s Disease (AD) pathology. However, objective measures of decreased alertness have not been examined in the context of AD. Here, we examined performance on the psychomotor vigilance task (PVT) in relation to AD pathology as indexed by AD biomarkers in cerebrospinal fluid (CSF), among individuals with and without OSA.MethodForty‐eight cognitively unimpaired adults (32 women), mean age 66.3±7.9 years, enrolled in the Wisconsin Alzheimer’s Disease Research Center (ADRC) completed a multifaceted sleep assessment. Presence and severity of OSA was evaluated using WatchPAT at‐home overnight recordings. Habitual sleep‐wake patterns were assessed using actigraphy. Neurobehavioral alertness was quantified using the 10‐minute PVT. CSF biomarkers were quantified using the exploratory Roche NeuroToolKit assays, a panel of automated robust prototype immunoassays (Roche Diagnostics International Ltd). Generalized linear models examined associations between AD biomarkers, apnea‐hypopnea index (AHI), and PVT performance. Primary AD biomarkers of interest were phosphorylated‐tau (p‐tau), total tau (t‐tau), and amyloid‐beta (Aβ) 42/40 ratio, measured in CSF. The primary PVT variable of interest was the mean response time of the 10% slowest responses, which is associated with daytime sleepiness and default mode network activity. Log transformations for PVT and AHI+1 were utilized for analysis. Covariates included age, sex, body mass index, total sleep time, sleep efficiency, APOEε4 status, years of education, and parental history of AD.ResultAHI was associated with lower Aβ 42/40 (β=‐0.005,p=0.03) and higher p‐tau (β=2.22,p=0.03), but not t‐tau (β=20.28,p=0.20). Significant AHI*PVT interactions were observed for p‐tau (p=0.0002) and t‐tau (p=0.02), but not for Aβ 42/40 (p=0.18). Specifically, among individuals with OSA (AHI&gt;5/hour;n=20), PVT performance was correlated with p‐tau (r=0.68,p=0.0009) and t‐tau (r=0.39,p=0.09), an association that was not observed in those without OSA in this preliminary dataset.ConclusionOSA was associated with amyloid and tau pathology, in individuals without cognitive impairment. Furthermore, PVT performance may be an objective measure of sleepiness associated with elevated p‐tau and t‐tau among individuals with OSA. Replication and expansion of these findings in larger and longitudinal datasets are indicated. Funding: Supported by R03AG063274 and P30‐AG062715.

098 Effects of Metameric Display-Light on Alertness, Vigilance and Melatonin

Abstract Introduction Light emitted from visual displays can acutely increase alertness, improve cognitive performance and suppress melatonin in the evening. Here we tested the influence of different melanopic irradiance levels emitted by a metameric display setting on alertness, vigilance and salivary melatonin levels. Methods In an ongoing study, 37 healthy, male participants have so far completed a 2-week study protocol. Volunteers were assigned to one of four luminance groups which differed in brightness levels (27 cd/m2 - 280 cd/m2). Illuminance ranged between 7 and 85 lx. Within the four groups each volunteer was exposed to a low melanopic (LM) and a high melanopic condition (HM). The LM and HM differed in melanopic irradiance (ca. 3-fold change), but matched in terms of cone excitation (metamers). Before, during and after the light exposure, volunteers performed a psychomotor vigilance task (PVT). Subjective alertness and melatonin levels were continuously measured in half-hourly intervals throughout scheduled wakefulness in the 17-h in lab study. Results Preliminary analysis yielded an overall alerting response in the HM vs. the LM condition (p&amp;lt;0.05) concomitant with a trend of reduced melatonin levels in HM vs. LM (p=0.08). So far, we could not observe a difference in PVT performance for HM and LM (Reaction time responses between 100 and 500 ms). Since we are still lacking statistical power in the ongoing study, we cannot yet satisfactorily interpret interaction effects between melanopic condition and brightness. Conclusion Our data indicate that rather low brightness levels of high melanopic display light impacts alertness and melatonin levels in the evening. Thus, metameric low melanopic display light may be a promising method to attenuate activating properties of evening light on circadian physiology without affecting visual appearance. Support (if any) This project is funded by the Swiss National Science Foundation (SNSF).

Nurses and Night Shifts: Poor Sleep Quality Exacerbates Psychomotor Performance.

In Europe, 40% of health-care employees are involved in shift work. The altered sleep/wake rhythm of night-shift nurses is also associated with deteriorated cognitive efficiency. In this study, we examine the effects of the night shift on psychomotor performance, sleepiness, and tiredness in a large sample of shift-working nurses and evaluated if poor sleep quality, sex, age, or years on the job could impact on a better adaptation to shift work. Eighty-six nurses with 8-h-rapidly-rotating-shifts were evaluated at the end of three shifts (morning/afternoon/night) for sleepiness and tiredness. Sleepiness, as measured by the Karolinska Sleepiness Scale, and tiredness, as measured by the Tiredness Symptoms Scale, were more pronounced after the night shift. These increases were paralleled by lower attentional performance on the psychomotor vigilance task (PVT) after the night shift. While sex, age, and years on the job did not affect PVT performance after the night shift, lower sleep quality (Pittsburgh Sleep Quality, PSQI > 5) was associated with decreased performance. The high prevalence of altered sleep quality showed that nurses, and shift workers in general, are at risk for a poor sleep quality. The evaluation of sleep quality through PSQI could represent a rapid, inexpensive tool to assess health-care workers assigned to rotating night shifts or to evaluate nurses who coped poorly with night-shift work.