Study objectives: To determine whether the increased wake within a bedrest episode in healthy older people is due to an increased number and/or increased duration of awakenings by evaluating the rates of transition between sleep and wake bouts within a bedrest episode.
Design: Analysis of previously reported polysomnographic data from 13 older and 11 younger healthy individuals scheduled to sleep at many different phases of the endogenous circadian cycle during conditions of forced desynchrony (18.7 hours wake: 9.3 hours bedrest) of the circadian and wake-bedrest cycles.
Setting: General clinical research center
Patients or participants: None.
Interventions: None.
Measurements and results: Older subjects had an approximately 2.7-fold increased rate of awakening from sleep but the same rate of falling back asleep as younger subjects. These differences between young and older individuals were observed at most circadian phases and throughout the bedrest episodes. In addition, the circadian variation in transition rates was greater in younger than older subjects.
Conclusions: These results suggest that the reduced consolidation of sleep within a bedrest episode is due to difficulties remaining asleep, rather than falling asleep once awake, and is a primary change in sleep with aging.