Abstract
Sleep paralysis consists of episodes of inability to perform voluntary movements either at sleep onset (hypnagogic form) or on awakening (hypnopompic form), and from the pathophysiological point of view, it is a borderline state between dissociated REM sleep and wakefulness. Episodes typically last 1-3 minutes, however, in spells it can last longer.
Sleep paralysis occurs in one of the following three conditions. (1) Isolated paralysis appearing in 6-40% of otherwise healthy subjects at least once in their lifetime. It usually occurs as a result of irregular sleep - wake patterns – most frequently in shift workers or in individuals with recurrent exposure to jet lag. (2) The familial form of isolated paralysis is a relatively rare condition occurring in multiple cases in families. (3) Sleep paralysis is one of the symptoms of the narcoleptic tetrad.