Information about Sleep Paralysis


Sleep Paralysis as Nightmare

Sleep Paralysis in Literature: Le Horla


SP & Narcolepsy

SP in Myth & Legend

The Hallucinations

The Intruder

The Incubus

Bodily Experiences

Prevention & Coping


 A webpage about

Sleep Paralysis


Associated Hypnagogic and Hypnopompic Experiences 

In this site we provide information on the many features of sleep paralysis and associated experiences. The material below has been gathered from many sources, including our own research into the sleep paralysis experience. 


If you have experienced episodes of sleep paralysis, it will be very much appreciated if you will take some time to fill out the Waterloo Unusual Sleep Experiences Scale (English) (Français)

before reading on. You might actually find the information provided on this web site more relevant if you take a few minutes to fill out the questionnaire now.



Publications making use of the Waterloo Unusual Sleep Experiences Scale

Cheyne, J. A. (2010). Recurrent Isolated Sleep Paralysis. In M. Thorpy & G. Plazzi (Eds.), Parasomnias and other movement-related sleep disorders. Amsterdam, Elsevier.

Cheyne, J. A. & Girard, T. A. (2009). The body unbound: Vestibular-motor hallucinations and out-of-body experiences. Cortex, 45, 201-215.

Cheyne, J., A., (2009). Hypnagogic and hypnopompic hallucinations. In T. Bayne, A. Cleeremans, & P. Wilken, (Eds.), Oxford Companion to Consciousness. Oxford: Oxford University Press.

Abrams, M. P., Mulligan, A. D., Carleton, A. D., Asmundson, G. J. G. (2008). Prevalence and correlates of sleep paralysis in adults reporting sexual abuse. Journal of Anxiety Disorders, 22, 1535-1541.

Solomonova, E., Neilsen, T., Stenstrom, P. Simard, V. Frantova, E., & Donderi, D. (2008). Sensed Presence as a correlate of sleep paralysis distress, social anxiety and waking state. Consciousness and Cognition, 17, 49-63.

Cheyne, J. A. & Girard, T. A. (2007). The nature and varieties of felt presence experiences: A reply to Nielsen. Consciousness and Cognition, 16, 984-991.

Cheyne, J. A. & Girard, T. A. (2007). Paranoid delusions and threatening hallucinations: A prospective study of hypnagogic/hypnopompic hallucinations during sleep paralysis. Consciousness and Cognition, 16, 959-974.

Girard, T. A., Martius, D. L. M. A., & Cheyne, J. A. (2007). Mental representation of space: Insights from oblique distribution of hallucinations. Neuropsychologia, 45, 1257-1269.

Girard, T. A. & Cheyne, J. A. (2006). Timing of spontaneous sleep paralysis episodes. Journal of Sleep Research, 15, 222-229.

Cheyne, J. A. (2006). Sleep paralysis: State transition disruption and narcolepsy. In C. Bassetti & E. Mignot (Eds.), Narcolepsy and Hypersomnia, New York: Dekker.

Otto, M. W., Simon, N. M., Powers, M., Hinton, D., Zalta, A. K., Pollack, M. H. (2006) Rates of isolated sleep paralysis in outpatients with anxiety disorders. Journal of Anxiety Disorders, 20, 687-693.

Cheyne, J. A. (2005). Sleep paralysis episode frequency and number, types, and structure of Associated Hallucinations. Journal of Sleep Research, 14, 319-324.

McNally, R. J. & Clancy, S. A. (2005a). Sleep Paralysis in Adults reporting repressed, recovered, or continuous memories of childhood abuse. Journal of Anxiety Disorders, 19, 595-602.

McNally, R. J. & Clancy, S. A. (2005b). Sleep paralysis, sexual abuse and space alien abduction. Transcultural Psychiatry, 42, 113-122.

Simard, V. & Nielsen, T. A. (2005). Sleep paralysis-associated sensed presence as a possible manifestation of social anxiety. Dreaming, 15, 245-260.

Cheyne, J. A. & Girard, T. A. (2004). Spatial characteristics of hallucinations associated with sleep paralysis. Cognitive Neuropsychiatry, 9, 281-300.

Girard, T. A., & Cheyne, J. A. (2004). Individual differences in lateralization of hallucinations associated with sleep paralysis, Laterality, 9, 93-111.

Cheyne, J. A. (2003). Sleep paralysis and the structure of waking-nightmare hallucinations. Dreaming, 13, 163-179.

Cheyne, J. A. (2002) Situational factors affecting sleep paralysis and associated hallucinations: Position and timing effects. Journal of Sleep Research, 11, 169-177.

Cheyne, J. A. (2001). The ominous numinous: Sensed presence and ‘other’ hallucinations. Journal of Consciousness Studies, 8, 133-150. (Also published in E. Thompson (Ed.) (2001). Between Ourselves: Second-Person Issues in the Study of Consciousness. Exeter, UK: Imprint Academic)

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.

Cheyne, J. A., Newby-Clark, I.R., & Rueffer, S.D. (1999). Sleep paralysis and associated hypnagogic and hypnopompic experiences. Journal of Sleep Research, 8, 313-318.



Related Research

You may also be interested in participating in the following study.


Study on Familial Sleep Paralysis

Patients that suffer from frequent episodes of sleep paralysis.  Sleep paralysis occurs upon awakening or just falling asleep when patient is awake but unable to move.  These experiences are often scary and can also involve unusual feelings. For some patients, these episodes occur frequently and appear to run in families. Adult subjects (at least 18 years of age) who experience sleep paralysis on a frequent basis (at least once/year) AND have other family members who also experience sleep paralysis frequently.  Taking part in this research study would involve a medical history and a saliva collection. Contact:  Dr. Mark Wu,* <>  (*Formerly at the University of Pennsylvania's Health System now at Johns Hopkins) <>


Abstracts of our published work

Some statistics from the WUSES

A newsletter



You may also be interested in another of our projects on

Attention and Inattention:

Attention lapses in Everyday Life


Locations of visitors to this page


Other Web Resources for Sleep Paralysis


·         Hags and Nightmares: Michele Ernsting - Radio Netherlands: Text and Audio

·         Sleep Paralysis: Dreams and Nightmares

·         General Information on Sleep Paralysis (

·         Sleep Paralysis: William Dement

·         Sleep Paralysis and Lucid Dreams: Jorge Conesa

·         Sleep Paralysis: Skeptic’s Dictionary

·         Personal Accounts of Sleep Paralysis: BISleep

·         Hallucinations and Illusions of Non-psychiatric Aetiologies: Ramon Boza