Changes in sleep timing and duration during and after rotating shifts can be explained without the assumptions of the shifts of the circadian phase of sleep and loss of its circadian control.

purposeMorning and night rotating shifts cause misalignment of the sleep-wake cycle in relation to the biological night. We examined whether, to explain sleep timing and duration during and after these rotating shifts, it is necessary to propose the shifts of the circadian phase of sleep and disruption of its circadian control.

methodsA model of sleep-wake regulation was applied to simulate sleep times reported by German shiftworkers for 6 phases of the cycle of rotating shiftwork (days on and off for morning, evening, and night shifts).

resultsTo simulate these sleep times, the assumptions of circadian phase shifts and loss of the permanent control of the circadian clocks over the sleep-wake cycle were not required. The simulations additionally predicted sleep times recently reported by Uruguayan and Norwegian shiftworkers for these 6 phases of shiftwork.

conclusionsSleep deprivation during night shifts and irrecoverable loss of sleep prior to morning shifts can be responsible for the adverse health effects of rotating shiftwork. The extensions of the wake phase of the sleep-wake cycle before morning shifts and during night shifts can directly compromise the chronophysiological organization of the organism via disturbing the peripheral rather than central circadian clocks governing the sleep-wake cycle.