The Circadian Pattern of Unrestricted Sleep and Its Relation to Body Temperature, Hormones, and Alertness.
NIOSH 1981 Jul:605-624
Results of studies on circadian patterns of unrestricted sleep and its effect on subjective alertness, temperature, and hormone excretions were presented. Six subjects aged 29 to 45 years started sleep at 2300 hours on the first day. Each following sleep session was delayed for 4 hours relative to the preceding session. Subjects ended with the seventh bedtime at 2300 hours after 40 hours awake. Individuals slept until they felt that sleep was no longer needed. Sleep length showed a highly significant circadian variation with maximum sleep after evening bedtimes. Sleep after morning bedtimes was reduced to approximately half. Electroencephalographic parameters showed a highly significant circadian variation with maximum sleep following evening bedtimes. Absolute amounts of stage 2 and rapid eye movement sleep showed the same pattern as total sleep. Slow wave sleep did not vary significantly across bedtimes. For adrenaline (51434) excretion, there was a pronounced circadian rhythm during waking, while during sleep there was almost a complete shutoff, mainly during daytime. Noradrenaline (149951) excretion showed no rhythmicity. Cortisol (53065) and melatonin (73314) elimination followed the circadian pattern. Body temperature alteration during sleep was a direct function of circadian phase. Self rated sleepiness showed a pronounced circadian pattern peaking in early morning. The pronounced circadian pattern of sleep length suggested regulation by an underlying oscillation of arousal. Sleep during the rising portion of temperature rhythm was greatly shortened, while sleep on the descending portion was lengthened. The authors conclude that sleep characteristics are to a large extent a direct function of circadian phase of an underlying arousal rhythm.
Sleep-deprivation; Circadian-rhythms; Urinalysis; Hormones; Psychological-effects; Psychophysiology; Body-temperature; Health-protection;
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DHHS (NIOSH) Publication No. 81-127
The Twenty-Four Hour Workday: Proceedings of a Symposium on Variations in Work-Sleep Schedules, Division of Biomedical and Behavioral Science, NIOSH, U.S. Department of Health and Human Services, Cincinnati, Ohio, DHHS (NIOSH) Publication No. 81-127