Hypnagogic and hypnopompic hallucinations during sleep paralysis: neurological and cultural construction of the night-mare.

Sleep paralysis often involves vivid hypnagogic and hypnopompic experiences (HHEs) that closely resemble supernatural assault narratives across cultures. A three-factor structural model explains these experiences through REM neurophysiology. The Intruder factor involves sensed presence, fear, and hallucinations from midbrain hypervigilance. The Incubus factor includes chest pressure and breathing difficulties from motoneuron hyperpolarization affecting respiration perception. Both imply an alien 'other' consistent with occult narratives. The Unusual Bodily Experiences factor involves floating, out-of-body sensations, and bliss from conflicts between endogenous and exogenous activation related to body position. These findings connect to hallucinations in hypnosis and schizophrenia.

Study at a glance

Abstract

Hypnagogic and hypnopompic experiences (HHEs) accompanying sleep paralysis (SP) are often cited as sources of accounts of supernatural nocturnal assaults and paranormal experiences. Descriptions of such experiences are remarkably consistent across time and cultures and consistent also with known mechanisms of REM states. A three-factor structural model of HHEs based on their relations both to cultural narratives and REM neurophysiology is developed and tested with several large samples. One factor, labeled Intruder, consisting of sensed presence, fear, and auditory and visual hallucinations, is conjectured to originate in a hypervigilant state initiated in the midbrain. Another factor, Incubus, comprising pressure on the chest, breathing difficulties, and pain, is attributed to effects of hyperpolarization of motoneurons on perceptions of respiration. These two factors have in common an implied alien "other" consistent with occult narratives identified in numerous contemporary and historical cultures. A third factor, labeled Unusual Bodily Experiences, consisting of floating/flying sensations, out-of-body experiences, and feelings of bliss, is related to physically impossible experiences generated by conflicts of endogenous and exogenous activation related to body position, orientation, and movement. Implications of this last factor for understanding of orientational primacy in self-consciousness are considered. Central features of the model developed here are consistent with recent work on hallucinations associated with hypnosis and schizophrenia.