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.
Disorders of arousal (DoA) episodes, such as sleepwalking, are not a uniform state but involve varying levels of consciousness and responsiveness. In a retrospective questionnaire, 81% of 61 adult patients reported occasional conversations during episodes. Auditory stimulation during N3 sleep triggered episodes in only 7 of 157 trials, and only one patient indirectly responded to verbal prompts. Analysis of 364 home video-recorded episodes from 19 patients found 37 instances of discussion with a bed partner. Patients' ongoing mental content influenced their responses and perception of the outside world. These findings highlight limitations in current diagnostic criteria for DoA.
Alpha oscillations, a hallmark of waking visual perception when eyes close, do not reliably increase during lucid dreams when dreamers signal that their dream-eyes are closed. In 150 signals from 11 lucid dreamers, dream-eye closure was associated with fading visual content only about half the time. In three participants where visual content presence versus absence could be compared, increased alpha power accompanied momentary lack of visual content. Real-time reporting via sniffing patterns enables dynamic investigation of dream perception.