Abstract
Introduction
Sleep deprivation and circadian misalignment impairs human sensorimotor performance and reduces vigilant attention, which increases the potential for errors in occupations that ...require 24-hour operations. The psychomotor vigilance task (PVT) is the gold-standard measure for evaluating the impact of sleepiness on performance, however, it is not practical to administer in many operational environments, because it only provides a snapshot of performance and requires an individual to focus on the task for several minutes, multiple times over a work shift. As a result, passive, continuous monitoring of sleepiness is desirable for operational environments. The goal of the present study was to determine if complex oculomotor behavioral metrics track PVT performance during sleep deprivation.
Methods
Twelve healthy adults (mean age 24.8 ± 5.4 years; 6F) maintained a fixed schedule with 8.5 hours in bed for two weeks, during which they abstained from caffeine, alcohol, and other medications, followed by a ~24 hours constant routine laboratory stay. Participants completed the PVT and a radial step-ramp ocular tracking task hourly throughout the study. Twelve oculometrics were derived from smooth pursuit and saccadic eye movements collected through video-oculography and were compared to the PVT and Karolinska Sleepiness Scale (KSS) using linear regression and receiver operating characteristic curves.
Results
Nine oculometrics spanning pursuit, saccade, and directional motion processing performance correlated with the PVT and KSS (p < 0.05), including: (a) pursuit latency; (b) open-loop pursuit acceleration; (c) proportion smooth; (d) steady-state pursuit gain; (e) saccadic amplitude; (f) saccadic dispersion; (g) saccadic rate; (h) direction asymmetry; and (i) direction noise.
Conclusion
The oculometrics that we examined exhibited a distinct pattern that tracked PVT performance. Future studies should examine whether these metrics can be extracted through passive monitoring techniques.
Support
None
Abstract
Introduction
The psychomotor vigilance task (PVT) is sensitive measure of performance impairment arising from sleep loss and circadian misalignment. Some individuals maintain stable, good ...PVT performance during sleep restriction. It is unclear whether such individuals need less sleep or whether they are more resilient to the effects of sleep loss. We aimed to characterize the relationship between sleep duration and perceived sleep need with PVT performance under real-world conditions.
Methods
We collected actigraphy (MotionWatch-8, CamNtech), sleep logs, and the PVT (3–10 times/day) from airline pilots over a 34-day fixed work schedule that began with a baseline (mid-morning start) and then varied between early and late shifts. We split the participants into quartiles by mean baseline PVT and calculated sleep duration, self-reported sleep need, and percentage of sleep obtained relative to perceived need. We used ANOVA to compare sleep outcomes between quartiles.
Results
Thirty-seven participants completed the study (3F). Mean PVT scores over the entire study varied according to the baseline quartile split (quartile 1 Q1=229.1 ms ±84.9 SD; Q2=245.2 ms ±79.9; Q3=267.8 ms ±65.2; Q4=331.9 ms ±146.2) and remained stable irrespective of work schedule (e.g. Q1 performed best throughout). Actigraphy-derived sleep duration was significantly shorter among those in Q3 (6.4 h ±1.4; p=0.01) and Q4 (6.4 ± 1.5; p=0.01) compared to Q1 (6.8 h ±1.3). Participants in Q1 reported needing less sleep (7.7 h ± 0.7), but obtained a higher percentage of their self-reported sleep need (90%) on average compared to those in the other quartile categories (Q2=7.9 h ±0.6, 86%; Q3=8.0 h ±0.8, 81%; Q4=8.1 h ±0.7, 79%).
Conclusion
We found that participants with the best PVT performance reported needing less sleep, but obtained more sleep on average than those in the poorer performing quartiles. Our findings confirm that longer sleep duration is associated with better PVT performance and suggest that sleep need may differ between individuals who are defined resilient and vulnerable according to the PVT.
Support (If Any)
NASA Airspace Operations and Safety Program.
PDF