High-density EEG signature of NREM sleep parasomnia episodes.

NREM (non-rapid eye movement sleep) Parasomnia Episodes (PE) such as confusional arousals and sleep-talking represent abnormal wake-like behaviors initiated during sleep, with a known admixture of localized wake-like and sleep-like activities. Using high-density EEG (hdEEG), we quantified whole-scalp topographical EEG differences during PE compared to wakefulness and sleep. Twenty-two adults with NREM sleep parasomnia underwent 256-electrode hdEEG over two nights: a baseline night with ad-libitum sleep and an intervention night with recovery sleep after 25 h sleep deprivation. 79 PE occurred spontaneously or when triggered from NREM sleep during intervention nights. Spectral power of PE, sleep, and wake EEG was compared. Data from 70 PE (in 20 subjects) were of sufficient quality to be compared to sleep (matched for consciousness and sleep stage when possible) and wake. Delta and theta power during PE were significantly higher than wake but significantly reduced compared to sleep in central scalp regions. Additionally, beta/delta ratio values during PE were globally higher than during wake, but globally lower than during sleep. These findings suggest NREM PE feature a unique pattern of mixed cortical arousal and sleep, reflecting abnormal local regulation of sleep–wake boundaries in arousal disorder patients.