ABSTRACT
Sleep paralysis (SP) is a brief period of paralysis associated with REM occurring at sleep onset (hypnagogic) or offset (hypnopompic) (1,2). Descriptions and explanations of SP experiences have appeared in the scholarly, medical and scientific literature for at least 1500 years, often under the rubric of nightmare (3) and, more recently, as part of the narcoleptic tetrad/pentad (1). The nature of the relation between SP and narcolepsy is a focus of the second part of the present chapter.
