Sleepwalking (Somnambulism) is characterized by complex sometimes semi-purposeful activity that arises from Stages 3 and 4 sleep, usually during the first hour or two of sleep. The affected person may sit up in bed or arise and walk about, occasionally sustaining an injury. When awakened during the episode or after awakening for the day, the patient has no recollection for what occurred.

Sleep terrors (pavor nocturnus) are characterized by the affected individual screaming during awakening and then often jumping up from bed in terror. Initially there is disorientation. On questioning, a recollection of experiencing intense fear is described rather than the specifics of a typical dream. Sleep terrors arise from Stage 3 and 4 sleep and, like somnambulism, are therefore most likely to occur during the first hour or two of sleep.

Sleep terrors and sleepwalking are more common in childhood than during adult years, but in some cases may begin or persist into adulthood. There is a tendency for these disorders to run in the family.

Sleepwalking is diagnosed through a combination of history and sleep studies including actigraphy and polysomnography.

Medications, such as bedtime benzodiazepines or sedating antidepressants, can suppress or eliminate episodes of sleepwalking or sleep terrors. Psychotherapy and drug treatment to reduce anxiety may also provide benefit.