Parasomnias are undesirable experiences or motoric phenomena that occur in association with sleep. We have described characteristics of parasomnia subtypes.This review is based on the authors' research and clinical experience, and articles identified by non-systematic searches of Pubmed.Parasomnias are categorized into disorders of arousal (non-REM sleep parasomnias), e.g. sleepwalking, sleep terrors and confusional arousals, parasomnias associated with REM sleep, e.g. nightmare disorder, REM sleep behaviour disorder and recurrent isolated sleep paralysis, and other parasomnias, e.g. sleep-related groaning, exploding head syndrome, sleep-related hallucinations and sleep-related eating disorder. Prevalences for the subtypes vary.Most parasomnias are especially common in children. Drug treatment is seldom necessary, but may be indicated in severe cases.