Classification of parasomnias

Abstract

Parasomnias are undesirable events or experiences occurring in sleep or during transitions to and from sleep. This category of disorders includes a varied set of disorders that can be classified based upon the sleep stage in which they predominantly occur. The non-REM parasomnias include disorders of arousal and sleep–wake transition. These are confusional arousals, sleepwalking (including sleep sex), and sleep terrors. Parasomnias occurring predominantly during REM sleep include REM sleep behavior disorder, recurrent isolated sleep paralysis, and nightmare disorder. The third category, parasomnias that occur independent of sleep stage, includes sleep related dissociative disorder, sleep related groaning (catathrenia), exploding head syndrome, sleep related hallucinations, sleep related eating disorder, and sleep enuresis, as well as parasomnias due to drugs or substances and parasomnias due to a medical condition. As further research clarifies the pathophysiology of these highly varied disorders, it is likely this scheme for classifying parasomnias will continue to evolve.