Geomagnetic, Cross-Cultural and Occupational Faces of Sleep Paralysis: An Ecological Perspective

S leep paralysis (SP) is a rapid eye movement (REM) sleep disturbance and concurrent dream phenomena which usually occurs at sleep onset, upon awakening, or during the transition between REM and awakening in narcoleptics and the normal population (1-4). The dreamer wakes up during or from REM sleep and, in full awareness, recognizes and experiences the atonic condition that accompanies this sleep cycle. In addition to the atonic state, a commonly reported hallucination is the feeling of a presence (FOP) or entity in the room in which the individual sleeps. This hypnagogic hallucination may be sensed as threatening, likely giving rise to the cross-cultural folklore belief of the nightmare; the Old Hag; the incubus (Europe); Pesadilla (Spain/Latin America); Tindihan (Indonesia); Night marchers (Hawaii); Doppelganger (Germany); and Kanashibari (Japan) (5-8). Other experiences associated with SP events include microsomatognosia (9); hearing voices or sounds (rumbling, hissing or crackling); odd vestibular sensations (sinking in the bed, gliding above the body or about the room, or the body twisting itself into a tight ball); abdominal or chest pain; and somatosensory events ("hands" caressing, pulling or pushing one s body) (10-12). Another typical report in SP symptomology is the continuation of dreaming into a lucid dream (1013). The present review updates a projected ten-year study on SP (12), and still finds evidence that SP is a normally occurring sleep disturbance reported by average individuals with no self-reported history of mental disease, who do not use anxiolytic medication, and who represent many cultures. Notwithstanding these global and mundane cases, a recent and comprehensive study by Ohayon, Zulley, Guilleminault and Smirne (14) reported that the prevalence of SP without other "easily identified and treated" factors is only about 1.7% and/or has a lifetime prevalence of SP at 6.2% in German and Italian populations (N=8,085). Their study, Geomagnetic, Cross-Cultural and Occupational Faces of Sleep Paralysis: An Ecological Perspective