Sleep paralysis and false awakenings are intermediate states between REM sleep and wakefulness. In a sleep-laboratory study of five participants, polysomnography recordings captured five sleep-paralysis episodes and two false awakenings. During sleep paralysis, 70.8% of 3-second mini-epochs showed theta brain waves (compared to 89.7% in normal REM sleep and 21.2% in wakefulness), 93.8% had chin-muscle atonia (vs 89.7% in REM and 33.3% in wakefulness), and 6.9% contained rapid eye movements (vs 11.9% in REM and 8.1% in wakefulness). The electroencephalography spectrum during sleep paralysis was intermediate between wakefulness and REM sleep for alpha, theta, and delta frequencies, while beta frequencies matched normal REM sleep.
Three patients with non-REM parasomnias experienced episodes of Cotard delusion—believing they were dead or dying and unable to perceive their bodies as their own. These nihilistic mentations occurred during confusional arousals from sleep and were accompanied by panic. EEG source analysis indicated right-hemispheric hypoactivity during the episodes. The authors argue that aberrant activation of the salience network and default mode network—two major intrinsic networks of wakefulness—underlies these states. Such dreamlike mentations are rarely remembered and likely underreported, but can cause significant distress and worsen clinical outcomes if unaddressed.