Non–Rapid Eye Movement Sleep Arousal Disorders 401
sexual activity (e.g., masturbation, fondling,  groping, sexual intercourse) occur as complex
behaviors arising from sleep wi thout conscious awareness. Th is condition is more common
in males and may result in serious interper sonal relationship problems or medicolegal
consequences.
During a typical episode of sleep terrors, th ere is often a sense of overwhelming dread,
with a compulsion to escape. Although fragmentary vivid dream images may occur, a story-
like dream sequence (as in nightmares) is not reported. Most commonly,  the individual does
not awaken fully, but returns to sleep and has amnesia for the episode on awakening the next
morning. Usually only one episode will occur on any one night. Occasionally several episodes
may occur at intervals throughout the night. Th ese events rarely arise during daytime naps. 
Prevalence
Isolated or infrequent NREM sleep arousal disorders are ve ry common in the general pop-
ulation. From 10% to 30% of children have had at least one episode of sleepwalking, and
2%–3% sleepwalk often. The prevalence of slee pwalking disorder, marked by repeated ep-
isodes and impairment or dist ress, is much lower, probably  in the range of 1%–5%. The
prevalence of sleepwalking episodes (not sleepwalking disorder) is 1.0%–7.0% among
adults, with weekly to monthly episodes o ccurring in 0.5%–0.7%. The lifetime prevalence
of sleepwalking in adults is 29.2%, with a p ast-year prevalence of sleepwalking of 3.6%.
The prevalence of sleep terrors in the general population is unknown. The prevalence