In a recent issue of the Annals of Neurology, the official journal of the American Neurological Association, authors Antonio Zadra, Mathieu Pilon and Jacques Montplaisir explain how they evaluated 40 suspected sleepwalkers. Each was referred to the Sleep Research Centre at Sacré-Coeur Hospital, a Université de Montréal teaching hospital, between August 2003 and March 2007.
"Our study found that sleep deprivation can precipitate sleepwalking in predisposed individuals," said lead investigator Antonio Zadra. "Sleepwalkers are best to maintain a regular bedtime and avoid sleep deprivation if they wish to steer clear of somnambulism."
One night of sleep, one night awake
Subjects who took part in the study agreed to have their baseline sleep patterns monitored during an initial all-night assessment. During a subsequent visit, patients were kept awake for the entire evening and remained under constant supervision.
Recovery sleep was allowed the next morning after patients had been awake for 25 hours. Subjects were videotaped during each sleep period as the research team evaluated their behaviour, which ranged from playing with bed sheets to trying to jump over the bed rails. Subjects were evaluated on a three-point scale based on the complexity of their actions.
Results were striking. During baseline sleep, only half of patients exhibited some 32 behavioural episodes. During recovery sleep, 90 percent of patients demonstrated a total of 92 behavioural episodes.
The study also found that sleepwalkers, previously thought to suffer from an inability to sustain slow-wave or deep sleep, had increased difficulty in passing from slow-wave sleep to another sleep stage or to be fully awake following sleep deprivation. "This research also reveals that objective methods can now be used for investigating and diagnosing sleepwalking," said Dr. Zadra.