Sleep deprivation a sleepwalking cause; cruel cut no defense

For people predisposed to sleepwalking, keeping them awake for a full day can trigger a sleepwalking episode when they are finally allowed to sleep.

This represents a valuable tool for diagnosing the condition, according to Canadian researchers. They point out in the Annals of Neurology that the diagnosis of somnambulism is difficult, because sleepwalking episodes rarely occur spontaneously in the sleep laboratory. Nonetheless, sleep specialists may be called on to verify a diagnosis of somnambulism, sometimes for legal reasons, as people may unwittingly injure themselves or act aggressively while sleepwalking.

Dr Antonio Zadra and colleagues at the University of Montreal tested the idea that restricting sleep might trigger somnambulism in a group of 40 patients thought to have the tendency to sleepwalk. Fifteen reported injuring themselves during such episodes.