Sleep and circadian rhythm disturbances in patients with delayed sleep phase syndrome

Study Objectives: The objective of this study was to clarify sleep characteristics and pathophysiology in patients with delayed sleep phase syndrome (DSPS), which is a major circadian rhythm sleep disorder subtype. Design: Polysomnography was performed for 2 consecutive nights and core body temperature was sampled for 7 consecutive days, including the polysomnography study period, in all subjects. Findings were compared and statistically analyzed between patients with DSPS and matched controls. Setting: Sleep disorders unit in National Center Hospital. Participants: 11 DSPS patients and 11 age-matched healthy volunteers. Interventions: N/A Measurements and Results: Sleep latency, total sleep time, wakefulness after sleep-onset, and the amount and percentage of Stage 1 sleep were greater in DSPS patients than in volunteers. Sleep efficiency and the amount and percentage of slow wave sleep were lower in DSPS patients than in volunteers. Compared with the healthy volunteers, DSPS patients showed a decreased number and different temporal distribution of high voltage and low-frequency delta waves. The time of minimum body temperature appeared earlier in the sleep phase for the patients than for the volunteers. Significant correlation was found between the amount of slow wave sleep and the time from sleep onset to minimum body temperature and between the amount and percentage of slow wave sleep and time from minimum body temperature to sleep offset. Conclusions: Disturbances were found in the sleep structure of patients with DSPS, and these disturbances were related to the discrepancy between patients and controls in the phase relationship difference between sleep and core body temperature rhythms.