[Disorders of arousal]

There are three slow wave sleep (SWS) parasomnias: confusional arousal, sleepwalking and night terrors grouped together in arousal disorders because impaired arousal from sleep has been postulated as a cause of these disorders. The onset of these disorders at the beginning of the night in slow wave sleep (SWS) is a typical feature. Night sleep is characterised by a great sleep fragmentation specially in SWS, and by a very strong SWS intensity reflected by both an increase of slow wave activity (SWA) before the parasomnia and a slower decay of wave activity (SWA) during the night. An abnormal deep sleep associated with a high SWS fragmentation is responsible for the occurrence of arousal disorders parasomnias.