Comparison of subjective and objective assessments of sleep in healthy older subjects without sleep complaints

Older adults have reduced sleep quality compared with younger adults when sleeping at habitual times and greater sleep disruption when their sleep is at adverse times. The purpose of this analysis was to investigate how subjective measures of sleep relate to objectively recorded sleep in older subjects scheduled to sleep at all times of day. We analyzed data from 24 healthy older (55-74 years) subjects who took part in a 32-day inpatient study where polysomnography was recorded each night and subjective sleep was assessed after each scheduled wake time. The study included baseline nights and a forced desynchrony (FD) protocol when the subjects lived on a 20-h rest activity schedule. Our postsleep questionnaire both included quantitative and qualitative questions about the prior sleep. Under baseline and FD conditions, objective and subjective sleep latency were correlated, subjective sleep duration was related to slow-wave sleep and wake after sleep onset, subjective sleep quality was related to stage 1 and 2 sleep, and sleepiness and refreshment at wake time were related to duration of premature awakening. During FD, most measures of objective and subjective sleep varied with circadian phase and many additional correlations between objective and subjective sleep were present. Our findings show that when sleeping at habitual times, these healthy older subjects did not perceive their generally poor sleep quality, but under FD conditions where sleep quality changed from day-to-day their subjective sleep ratings were more associated with their objective sleep.