A Webpage about Sleep Paralysis and Associated Hypnagogic and Hypnopompic Experience

This is a Website created by Dr A Cheyne, from Waterloo University in Canada.  Dr Cheyne’s research is in Consciousness and Cognition with a particular interest in Sleep Paralysis.

This webpage http://watarts.uwaterloo.ca/~acheyne was developed a few years ago and provides an overview of the features of sleep paralysis in its various forms.  Patient experiences of sleep paralysis, ranging from mild to extremely disturbing are presented and analysed.  On the more philosophical/psychological side there is also an attempt to relate the physiological aspects of this sleep disorder to the aspects of our cultural heritage.


The experiences of sufferers of sleep paralysis have been ‘explained’ in many ways by popular culture.  This ranges from demonic possession to alien abduction.  There is in fact a substantial body of literature (and web / YouTube information) relating the disorder to the occult.  Sleep paralysis is often a very frightening experience to those with no knowledge of its physiology so it is not surprising that it could be interpreted in this way.

The site also refers to examples of what is obviously an experience of sleep paralysis in fictional literature. Examples of writing by Montpassant in the 19th century and cultural folk stories of the ‘Old Hag’ told in Newfoundland are related to Sleep Paralysis experiences.  As with “Pickwickian Syndrome”, fiction can often accurately document a real experience or condition even before it is recognised by science or medicine.


Nightmare (Detail)  Henry Fuseli



This website is an interesting mix of facts about sleep paralysis along with an interpretive view of how this disorder has become part of our cultural/psychological heritage.  For those interested in the psyche as well as the physiology of sleep, the site presents an authoritative view of the disorder both past and present.


Sleep paralysis is not uncommon in patients with sleep disruption and fatigue and so will certainly be experienced by patients attending Sleep Clinics whether or not it is discussed at presentation.  This website presents a lot of interesting information on a little studied sleep disorder.  While the site will be of more interest to those with a philosophical bent, a lot of research and patient experience is presented which will be of interest to all.

Sleep Paralysis Facts:

  • 'Sleep paralysis is a REM sleep parasomnia characterised by an inability to perform voluntary movements, associated with marked anxiety and occurs either at sleep onset (hypnagogic form) or on awakening (hypnopompic form).
  • Sleep paralysis attacks last a few minutes, do not involve respiratory and ocular muscles, are fully reversible, and often are accompanied by terrifying hallucinatory phenomena.
  • Sleep paralysis may form part of the narcoleptic tetrad, but isolated sleep paralysis occurs independently from narcolepsy, sometimes in a familial form.
  • Sleep paralysis is polysomnographically characterized by the presence of mixed REM-like and wake EEG or EMG features’

From Medilink Clinical Summaries


Chris Maguire