On Varying Work/Sleep Schedules: Issues and Perspectives as Seen by a Sleep Researcher.
NIOSH 1981 Jul:403-417
Research on sleep quality, sleep quantity, and fragmentation of sleep was explored. In studies on naps, it was found that there was more rapid sleep onset and more total sleep time (TST) when the time for a 1 hour nap (1HN) fell in the last third of the night when body temperature was low. The amounts of sleep of Stage 2, Stage 4 and rapid eye movement (REM) increased with TST in the 1HN which was inversely related to body temperature. The structure of sleep for nap sleepers, who had 366 minutes TST in ten naps over a 40 hour period, and for gradual sleep reduction subjects was similar, however, nap sleep was less efficient. The fragmented sleep was not equivalent to unbroken sleep. The reduced sleep probably contributed to sleep complaints and fatigue, but was probably not the only cause. In gradual sleep reduction studies, it was shown that as sleep was reduced, sleep time was used more efficiently. Sleep reduction of 1 to 2 hours occurred with no marked changes in performance or mood. Changing the time of sleep was more important than the type or quantity of sleep. It appeared that morning sleep did not provide the same benefits as night sleep. In laboratory experiments, no significant relationship was found between the magnitude of arousal threshold and amounts of various sleep stages. The author states that a decrease in sleep quantity does not appear to be sufficient to cause extreme feelings of fatigue. The sleep complaint of shift workers may instead reflect problems and discontent, possibly induced by sleep being obtained at the wrong time in the normal 24 hour cycle.
Shift-work; Worker-health; Sleep-disorders; Sleep-deprivation; Psychological-fatigue; Job-stress; Mental-stress; Psychophysiology;
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