Polysomnographic diagnosis of sleepwalking: effects of sleep deprivation.

OBJECTIVE Somnambulism affects up to 4% of adults and constitutes one of the leading causes of sleep-related violence and self-injury. Diagnosing somnambulism with objective instruments is often difficult because episodes rarely occur in the laboratory. Because sleep deprivation can precipitate sleepwalking, we aimed to determine the effects of 25 hours of sleep deprivation on the frequency and complexity of somnambulistic episodes recorded in the laboratory. METHODS Thirty consecutive sleepwalkers were evaluated prospectively by video-polysomnography for one baseline night and during recovery sleep after 25 hours of sleep deprivation. Ten sleepwalkers with a concomitant sleep disturbance were investigated with the same protocol. RESULTS Sleepwalkers experienced a significant increase in the mean frequency of somnambulistic episodes during postdeprivation recovery sleep. Postsleep deprivation also resulted in a significantly greater proportion of patients experiencing more complex forms of somnambulism. Sleep deprivation was similarly effective in 9 of the 10 patients presenting with a comorbid sleep disturbance. Combining data from all 40 patients shows that whereas 32 episodes were recorded from 20 sleepwalkers (50%) at baseline, recovery sleep resulted in 92 episodes being recorded from 36 patients (90%). INTERPRETATION The findings support the view that sleepwalkers suffer from a dysfunction of the mechanisms responsible for sustaining stable slow-wave sleep and suggest that these patients are particularly vulnerable to increased homeostatic sleep pressure. Strong evidence is provided that 25 hours of sleep deprivation can be a valuable tool that facilitates the polysomnographically based diagnosis of somnambulism in predisposed patients.