Search

> 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.

Citation: Cheyne, J.A., Rueffer, S.D. & Newby-Clark, I.R. (1999) "Hypnagogic and Hypnopompic Hallucinations during Sleep Paralysis: Neurological and Cultural Construction of the Night-Mare" Consciousness and Cognition 8, 319-337.

> Sleep paralysis (SP) is a dissociative state that occurs mainly during awakening. SP is characterized by altered motor, perceptual, emotional and cognitive functions, such as inability to perform voluntary movements, visual hallucinations, feelings of chest pressure, delusions about a frightening presence and, in some cases, fear of impending death. Most people experience SP rarely, but typically when sleeping in supine position; however, SP is considered a disease (parasomnia) when recurrent and/or associated to emotional burden. Interestingly, throughout human history, different peoples interpreted SP under a supernatural view. For example, Canadian Eskimos attribute SP to spells of shamans, who hinder the ability to move, and provoke hallucinations of a shapeless presence. In the Japanese tradition, SP is due to a vengeful spirit who suffocates his enemies while sleeping. In Nigerian culture, a female demon attacks during dreaming and provokes paralysis. A modern manifestation of SP is the report of “alien abductions”, experienced as inability to move during awakening associated with visual hallucinations of aliens. In all, SP is a significant example of how a specific biological phenomenon can be interpreted and shaped by different cultural contexts. In order to further explore the ethnopsychology of SP, in this review we present the “Pisadeira”, a character of Brazilian folklore originated in the country’s Southeast, but also found in other regions with variant names. Pisadeira is described as a crone with long fingernails who lurks on roofs at night and tramples on the chest of those who sleep on a full stomach with the belly up. This legend is mentioned in many anthropological accounts; however, we found no comprehensive reference on the Pisadeira from the perspective of sleep science. Here, we aim to fill this gap. We first review the neuropsychological aspects of SP, and then present the folk tale of the Pisadeira. Finally, we summarize the many historical and artistic manifestations of SP in different cultures, emphasizing the similarities and differences with the Pisadeira.