Are sleep paralysis and false awakenings different from REM sleep and from lucid REM sleep? A spectral EEG analysis.
STUDY OBJECTIVES To determine the polysomnography characteristics during sleep paralysis, false awakenings and lucid dreaming (which are states intermediate to REM sleep and wake but exceptionally observed in sleep laboratory) METHODS In 5 subjects, we captured 5 episodes of sleep paralysis (2 time marked with the ocular left right left right code normally used to signal lucid dreaming, 1 time marked by an external noise and 2 retrospectively reported) and 2 episodes of false awakening. The sleep coding (using three seconds mini epochs) and spectral EEG analysis were compared during these episodes and normal REM sleep as well as wakefulness in the same four among these five subjects, and vs. lucid REM sleep in four other patients with narcolepsy. RESULTS During episodes of sleep paralysis, 70.8 of mini epochs contained theta EEG rhythm, (vs. 89.7% in REM sleep and 21.2% in wakefulness) 93.8% contained chin muscle atonia (vs. 89.7% in REM sleep and 33.3% in wakefulness) and 6.9% contained rapid eye movements (vs. 11.9% in REM sleep and 8.1% in wakefulness) The EEG spectrum during sleep paralysis was intermediate between wakefulness and REM sleep in the alpha, theta and delta frequencies, whereas the beta frequencies were not different between sleep paralysis and normal REM sleep. The power spectrum during false awakening followed the same profile as in sleep paralysis. CONCLUSIONS The predominant theta EEG rhythm during sleep paralysis and false awakenings (with rare and lower alpha rhythm) suggests that the brain during sleep paralysis is not in an awake but in a dreaming state.
Journal of clinical sleep medicine JCSM official publication of the American Academy of Sleep Medicine