Circadian adaptation to fast and slow rotating shift systems.
Healthy male subjects were exposed to various shift systems. Adaptation and adjustment of the circadian systems were followed-up twice a week on so-called control days to reduce masking effects. With respect to the 24-hr minimum of rectal temperature and to the longest spontaneous sleep period on control days, the slower the shift system rotated and the later the individual circadian phase position was, the more subjects were able to follow the different shift systems. Subjects with stable phase shifts between the shift days always exhibited a phase shift of 1 hr per day.
D000222:Adaptation, Physiological; D000328:Adult; D001831:Body Temperature; D002940:Circadian Rhythm; D006801:Humans; D008297:Male; D012890:Sleep; D014937:Work; D014940:Work Schedule Tolerance