NEW YORK (Reuters Health) - Sleepwalking episodes appear more likely when sleepwalkers have their normal sleep patterns disrupted, Canadian researchers report.

"Our findings," Dr. Antonio Zadra told Reuters Health, "show that the combination of factors that deepen sleep -- like sleep deprivation -- and that fragment sleep -- like forced arousals with sounds -- increases sleepwalkers' probability of experiencing an episode."

Zadra and colleagues at the University of Montreal subjected ten sleepwalkers and ten "controls" to noises during normal sleep or recovery sleep after 25 hours of sleep deprivation. Subsequently these events were repeated after reversal of the order of normal sleep and sleep deprivation, the team explains in the medical journal Neurology

None of the controls experienced sleepwalking. However, three of the sleepwalkers experienced at least one episode under normal sleep conditions when they were subjected to noise, and all ten did so during recovery sleep when noises were applied.

These results support the recommendation that "sleepwalkers maintain regular sleep cycles, minimize sleep deprivation, and avoid potential environmental disturbances during sleep," Zadra concluded.