GOOD SLEEP - ITS TIMING AND PHYSIOLOGICAL SLEEP CHARACTERISTICS

The present study used short sleep episodes to explore the relation be tween subjective sleep quality, timing and physiological content of sl eep. Eight subjects participated in 18 4-h sleep episodes to provide 4 , 8, and 12h of prior time awake before bedtimes at six different time s of day in a sleep laboratory insulated from environmental disturbanc es. The results were analysed by ANOVAs and multiple regression techni ques. Subjective sleep quality, calmness of sleep, ease of falling asl eep, ability to 'sleep through', number of awakenings, and sleep laten cy showed a significant pattern of 'better' sleep with increasing prio r time awake and with closeness to the circadian minimum (nadir) of re ctal temperature (morning hours). 'Ease of awakening' in contrast, 'de creased' with increasing time awake and with closeness to the nadir/mo rning hours. Multiple regression analysis showed that subjective sleep quality was predicted by subjective calmness of sleep and ease of fal ling asleep, among the subjective measures, and by total sleep time (T ST) and slow-wave sleep (SWS - stages 3 + 4) among the physiological s leep measures. The subjective ease of awakening was predicted by slow- wave sleep (negatively) and the circadian maximum of rectal temperatur e. The results indicate that the duration of wakefulness prior to slee p and the timing of sleep determine its physiological expression, whic h in turn determines its subjective impression.