title: Temporal dynamics of ocular indicators of sleepiness across sleep restriction.
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.
authors: Division of Sleep Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA.
authors: Suzanne
authors: S
authors: Ftouni
authors: Shadab A
authors: SA
authors: Rahman
authors: Kate E
authors: KE
authors: Crowley
authors: Clare
authors: C
authors: Anderson
authors: Shantha M W
authors: SM
authors: Rajaratnam
authors: Steven W
authors: SW
authors: Lockley
mesh_terms: D000328:Adult; D001767:Blinking / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D004569:Electroencephalography; D053483:Eye Movement Measurements; D005143:Eyelids / Q000502:physiology*; D006801:Humans; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D057566:Self Report; D012890:Sleep / Q000502:physiology; D012892:Sleep Deprivation / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology; D055815:Young Adult
keywords: circadian rhythms; constant routine; electroencephalography; ocular measures; oculography; performance; sleep deprivation