Does REM sleep contribute to subjective wake time in primary insomnia? A comparison of polysomnographic and subjective sleep in 100 patients

Primary insomnia (PI) is characterized by low subjective sleep quality which cannot always be verified using polysomnography (PSG). To shed light on this discrepancy, subjective estimates of sleep and PSG variables were compared in patients with PI and good sleeper controls (GSC). 100 patients with PI (age: 42.57 +/- 12.50 years, medication free for at least 14 days) and 100 GSC (41.12 +/- 13.99 years) with a sex distribution of 46 men and 54 women in each group were included. Both PSG and questionnaire variables showed clear impairments of sleep quality in PI compared with GSC. The arousal index within total sleep time was increased, which was mainly because of a strong increase within rapid eye movement (REM) sleep. Subjectively, more PI than GSC subjects estimated wake times longer than obtained from PSG. Linear modeling analysis of subjective wake time in terms of PSG parameters revealed that in addition to PSG defined wake time, REM sleep time contributed significantly to subjective wake time. This REM sleep contribution was larger for PI than for GSC subjects. The findings suggest that REM sleep-related processes might contribute to subjectively disturbed sleep and the perception of waking time in patients with PI.