SP

When the body paralyzes itself outside of the REM cycle. Occasionally accompanied by hypnogogic hallucinations.
Often confused with REM atonia (REM atonia happens while in REM sleep)

• Sleep paralysis is a REM sleep parasomnia characterized 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 some minutes, do not involve respiratory and ocular muscles, are fully reversible, and often are accompanied by terrifying dream images.
• 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.Polysomnography, if performed, reveals the event to occur in a dissociated state with elements of REM sleep and wakefulness.
• Hallucinatory experiences may be present but are not essential to the diagnosis.
Info from post #1, here http://www.dreamviews.com/general-lu...citations.html

Actual SP is a condition affecting less than half of the population (7.6% general, more with sub-groups).

Aggregating across studies (total N=36,533), 7.6% of the general population, 28.3% of students, and 31.9% of psychiatric patients experienced at least one episode of sleep paralysis. Taken from post #2, here http://www.dreamviews.com/general-lu...citations.html

Related Links:
REM-Atonia
Sleep Paralysis Explained
Sleep Paralysis Demystified