REM sleep alterations in primary insomnia

Objectives: We previously (2008) found an association between REM sleep duration and perceived wakefulness in 81 patients with primary insomnia (PI) in addition to a clearly increased arousal index in REM sleep. The current study aimed to replicate and extend the previous findings. Methods: Polysomnogram (PSG) and subjective sleep quality questionnaire (Schlaffragebogen A, SFA) data of PI patients and matched good sleeper controls (GSC) were evaluated for group differences. Results: One hundred and fifty-six new PI patients could be matched to the same number of GSC (GSC; 60M, 96F; Mean age PI: 42.6 ± 12.4 years, GSC: 42.2 ± 13.4 years). PI patients had a higher wake time within bed time as well as lower REM and sleep stage 2 time. The association between perceived wake time and REM sleep time could be replicated in this new and larger group, as well as a clearly increased arousal index in REM sleep, while the arousal index in NREM sleep was significantly but less strongly increased. Conclusion: We postulate that the psychophysiological hyperarousal characteristic for primary insomnia is particularly expressed as a REM sleep alteration. REM sleep appears to be particularly vulnerable to pre-sleep worries, leading to increased retrospective recall of this time as wake time and a lower restorative sleep quality.