Ten adult sleepwalkers and 10 age-matched control subjects were investigated. After a screening night, participants were presented with AS during slow-wave sleep (SWS), REM, and stage 2 sleep either during normal sleep or daytime recovery sleep following 25 h of sleep deprivation. The AS conditions were then reversed one week later.
When compared to controls sleepwalkers necessitated a significantly higher mean AS intensity (in dB) to induce awakenings and arousal responses during REM sleep whereas the two groups鈥?mean values did not differ significantly during SWS and stage 2 sleep. Moreover, when compared to controls sleepwalkers had a significantly lower mean percentage of AS that induced arousal responses during REM sleep while the opposite pattern of results was found during SWS.
The data indicate that sleepwalkers have a higher auditory awakening threshold than controls, but only for REM sleep. These findings may reflect a compensatory mechanism of the homeostatic process underlying sleep regulation during sleepwalkers鈥?REM sleep in reaction to their difficulties maintaining consolidated periods of NREM sleep.