Babkoff H, Caspy T, Mikulincer M. Subjective sleepiness ratings: the effects of sleep deprivation, circadian rhythmicity and cognitive performance. Sleep 14: 534-539

Naval Health Research Center, San Diego, California 92138.
Sleep (Impact Factor: 4.59). 01/1992; 14(6):534-9.
Source: PubMed


Computerized self-report sleepiness scales were administered before and after cognitive testing in a 72-hour sleep deprivation study. The cognitive test battery was administered every 2 hours and took approximately 1-1.25 hours. Two computerized measures of subjective sleepiness were used, one a visual analog scale, the other a Hebrew version of the Stanford sleepiness scale. The results indicated that both accumulated sleep loss, circadian and ultradian (2 cycles/day) factors were significant in determining subjective estimates of sleepiness. The extent of the differences between subjective sleepiness ratings before cognitive testing and after testing was dependent upon the phase of the circadian cycle. These differences were greatest at approximately 0200-0600 hours and least around 1000 hours. A second low point occurred at 1800-2000 hours. Analysis by complex demodulation of the individual subjects' sleepiness rating curves indicated that the amount of variance accounted for by the circadian component increased significantly after cognitive testing.

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    • "Changes in subjective sleepiness occur during sleep deprivation and the circadian nadir (Babkoff et al., 1991; Gillberg et al., 1996). Moderate correlations have been found between subjective sleepiness scales and changes in vigilance, reaction time and lane drifting whilst driving following sleep deprivation (Gillberg et al., 1994; Horne and Baulk, 2004; Ingre et al., 2006b). "
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    ABSTRACT: Drivers are not always aware that they are becoming impaired as a result of sleepiness. Using specific symptoms of sleepiness might assist with recognition of drowsiness related impairment and help drivers judge whether they are safe to drive a vehicle, however this has not been evaluated. In this study, 20 healthy volunteer professional drivers completed two randomized sessions in the laboratory - one under 24h of acute sleep deprivation, and one with alcohol. The Psychomotor Vigilance Task (PVT) and a 30min simulated driving task (AusEdTM) were performed every 3-4h in the sleep deprivation session, and at a BAC of 0.00% and 0.05% in the alcohol session, while electroencephalography (EEG) and eye movements were recorded. After each test session, drivers completed the Karolinska Sleepiness Scale (KSS) and the Sleepiness Symptoms Questionnaire (SSQ), which includes eight specific sleepiness and driving performance symptoms. A second baseline session was completed on a separate day by the professional drivers and in an additional 20 non-professional drivers for test-retest reliability. There was moderate test-retest agreement on the SSQ (r=0.59). Significant correlations were identified between individual sleepiness symptoms and the KSS score (r values 0.50-0.74, p<0.01 for all symptoms). The frequency of all SSQ items increased during sleep deprivation (χ(2) values of 28.4-80.2, p<0.01 for all symptoms) and symptoms were related to increased subjective sleepiness and performance deterioration. The symptoms "struggling to keep your eyes open", "difficulty maintaining correct speed", "reactions were slow" and "head dropping down" were most closely related to increased alpha and theta activity on EEG (r values 0.49-0.59, p<0.001) and "nodding off to sleep" and "struggling to keep your eyes open" were related to slow eye movements (r values 0.67 and 0.64, p<0.001). Symptoms related to visual disturbance and impaired driving performance were most accurate at detecting severely impaired driving performance (AUC on ROC curve of 0.86-0.91 for detecting change in lateral lane position greater than the change at a BAC of 0.05%). Individual sleepiness symptoms are related to impairment during acute sleep deprivation and might be able to assist drivers in recognizing their own sleepiness and ability to drive safely.
    Full-text · Article · Sep 2013 · Accident; analysis and prevention
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    • "The tendency to sleep during the course of daily life, when intending to stay awake, represents a major new public health threat because it contributes to traffic and work accidents [1]. The main consequence of sleep deprivation is sleepiness, a condition in which human beings are subjectively, behaviorally and physiologically affected [2] [3] [4]. Many investigations of wake-sleep transition have been made. "
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    ABSTRACT: Sleepiness is a main causal factor for accidents and daytime malfunction. In this study we checked the feasibility of a new, ECG based method to detect the propensity to fall asleep while driving, using a passive Maintenance of Wakefulness Test (MWT) and an active Driving Simulation (DS) during increasing sleep deprivation conditions. Microsleeps (MS), and falling asleep (FA) events, were detected from electroencephalogram analysis. HRV was characterized using Time Domain analysis, Time Frequency Decomposition, Entropy, and Poincare plots. The first MS during MWT and DS represented a point for significant changes in all HRV measures. The first accident on DS occurred 2-7 minutes after the first MS. There are clear HRV markers that indicate sleepiness in sleep deprived subjects. Provided some of these variables show the same trends in sleepy non sleep deprived subjects, a threshold should be defined as to imminent danger of a driver falling asleep at the wheel.
    Full-text · Conference Paper · Oct 2010
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    • "In the morning nap and no nap conditions, participants had been awake for a minimum of 16 hours at 03:45 h. Decrements in simulated driving (Gillberg et al. 1996; Lenne et al. 1998; Philip et al. 1999; Arnedt et al. 2000), vigilance performance (Dorrian et al. 2000), and subjective sleepiness (Babkoff et al. 1991; Gillberg et al. 1996) have been observed previously after this amount of extended wakefulness. Decrements in psychomotor performance as a direct result of sleep deprivation generally occur after 17 hours awake (Dawson and Reid 1997). "
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    ABSTRACT: Sleepiness due to sleep loss and circadian factors can have a detrimental effect on performance, and contribute to road and workplace accidents. A brief nap taken during or immediately before a night shift may alleviate sleepiness both at work and on the road after work. This study investigated the effects of a 30-minute napping opportunity before or during an actual night shift. Performance was evaluated in three repeated-measures, crossover conditions; a nap prior to night shift (20:15 h), a nap during night shift (04:00 h) and no nap. Eight healthy nightshift workers completed a simulated driving task, the Psychomotor Vigilance Task and the Karolinska Sleepiness Scale at the start, end, and during an actual night shift. No significant improvement in performance was observed at the end of the night shift in either nap condition. A 30-minute napping opportunity was not sufficient to overcome the deleterious effects of sleep loss and circadian effects on performance during a first night shift, with no prior daytime sleep.
    Full-text · Article · Apr 2010 · Biological Rhythm Research
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