THE MEANING OF GOOD SLEEP - A LONGITUDINAL-STUDY OF POLYSOMNOGRAPHY AND SUBJECTIVE SLEEP QUALITY

The present study sought to investigate the meaning of subjectively go od sleep, using a longitudinal and intraindividual design. Eight subje cts slept in an isolation unit according to an irregular schedule of 6 h sleeps and 1 h naps, designed to give normal amounts of time in bed (1/3 of total), but variable sleep quality. Eight deeps and eight nap s were used for longitudinal simple and multiple regression analyses w ith standard polysomnographical sleep variables as predictors and subj ective sleep quality as dependent variables. The results showed that s ubjective sleep quality (and related variables) was closely related to sleep efficiency, but not deep stages. At least 87% efficiency was re quired for ratings of 'rather good' sleep. In addition, sleep quality ratings improved with closeness (of the awakening) to the circadian ac rophase (17.00-21.00 hours) of the rectal temperature rhythm. The subj ective ease of awakening differed from most other other variables in t hat it was related to low sleep efficiency. Objective and subjective h omologues of sleep length and sleep latency showed high mean intraindi vidual correlations (r = 0.55 and 0.64, respectively). It was conclude d that objective measures of sleep continuity were closely reflected i n perceived sleep quality and that sleep quality essentially means sle ep continuity.