Temporal Dynamics of Ocular Indicators of Sleepiness across Sleep Restriction. (December 2013)

• Record Type: Journal Article
• Authors: Ftouni, Suzanne; Rahman, Shadab A.; Crowley, Kate E.; Anderson, Clare; Rajaratnam, Shantha M.W.; Lockley, Steven W.
• Is Part Of: Journal of biological rhythms. Volume 28:Number 6(2013)
• Page Start: 412
• Page End: 424
• Publication Date: 2013-12
• Subjects: sleep deprivation -- ocular measures -- oculography -- electroencephalography -- performance -- constant routine -- circadian rhythms; Biological rhythms -- Periodicals; Circadian rhythms -- Periodicals; 571.77
• DOI: 10.1177/0748730413512257
• Languages: English
• ISSNs: 0748-7304

Abstract

The current study characterized the temporal dynamics of ocular indicators of sleepiness during extended sleep restriction. Ten male participants (mean age ± SD = 23.3 ± 1.6 years) underwent 40 h of continuous wakefulness under constant routine (CR) conditions; they completed the Karolinska Sleepiness Scale (KSS) and a 10-min auditory psychomotor vigilance task (aPVT) hourly. Waking electroencephalography (EEG) and ocular measures were recorded continuously throughout the CR. Infrared-reflectance oculography was used to collect the ocular measures positive and negative amplitude-velocity ratio, mean blink duration, the percentage of eye closure, and a composite score of sleepiness levels (Johns Drowsiness Scale). All ocular measures, except blink duration, displayed homeostatic and circadian properties. Only circadian effects were detected in blink duration. Significant, phase-locked cross-correlations ( p < 0.05 ) were detected between ocular measures and aPVT reaction time (RT), aPVT lapses, KSS, and EEG delta-theta (0.5-5.5 Hz), theta-alpha (5.0-9.0 Hz), and beta (13.0-20.0 Hz) activity. Receiver operating characteristic curve analysis demonstrated reasonable sensitivity and specificity of ocular measures in correctly classifying aPVT lapses above individual baseline thresholds (initial 16 h of wakefulness). Under conditions of sleep restriction, ocular indicators of sleepiness paralleled performance impairment and self-rated sleepiness levels, and demonstrated their potential to detect sleepiness-related attentional lapses. These findings, if reproduced in a larger sample, will have implications for the use of ocular-based sleepiness-warning systems in operational settings.