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Sleep-Wake, Endocrine and Temperature Rhythms in Man During Temporal Isolation.

Weitzman-ED; Czeisler-CA; Moore-Ede-MC
NIOSH 1981 Jul:105-124
Measurements of sleep waking function were made in human subjects for time periods ranging from 25 days to 6 months as part of a comprehensive multivariable study of chronophysiology of man in a time free environment with a nonscheduled daily pattern. Ten male subjects were individually studied. They were housed in a three room apartment without windows. This temporal isolation facility (TIF) included sound attenuated walls and a double door entrance, a closed circuit TV and voice intercom to monitor subjects' activities. Each subject kept a diary of sleep times and maintained a regular sleep wake schedule in accordance with their usual habits. An entrained condition of three or four scheduled 24 hour sleep wake periods preceded the nonscheduled free running segment. Parameters measured included polygraphic sleep characteristics, minute by minute body temperatures, and blood sampling for cortisol and growth hormone at intervals of approximately 20 minutes. Results were consistent with other studies indicating that human circadian rhythms freerun at period lengths greater than 24 hours, usually approximately 25 hours. Sleep to total time ratio remained constant during free running, but sleep stage organization changed such that rapid eye movement (REM) sleep occurred earlier and REM latency decreased. Total REM remained constant. Rectal temperature developed a 25 hour rhythm, and subjects usually slept when circadian temperature approached its nadir. Further drop in body temperature was noted at sleep onset. Plasma cortisol levels showed a component with a 6 to 8 hour phase advance relative to sleep onset and a component of cortisol inhibition during the first 2 to 3 hours of sleep. Secretion of growth hormone occurred just after sleep onset.
Worker-health; Work-intervals; Humans; Sleep-deprivation; Biological-rhythms; Psychological-effects; Physiological-response; Endocrine-function;
Publication Date
Document Type
Conference/Symposia Proceedings;
Fiscal Year
NTIS Accession No.
NTIS Price
Identifying No.
(NIOSH) 81-127
NIOSH Division
Source Name
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