Electroencephalographic slow waves prior to sleepwalking episodes

• Sleep EEGs were examined before somnambulistic episodes and non-behavioral awakenings.
• Slow-wave activity was greater prior to patients' somnambulistic episodes.
• Slow oscillations density was greater prior to patients' somnambulistic episodes.
• Increased slow-wave activity appears to be specific to sleepwalking episodes.

ObjectiveRecent studies have suggested that the onset of sleepwalking episodes may be preceded by fluctuations in slow-wave sleep electroencephalographic characteristics. However, whether or not such fluctuations are specific to sleepwalking episodes or generalized to all sleep–wake transitions in sleepwalkers remains unknown. The goal of this study was to compare spectral power for delta (1–4 Hz) and slow delta (0.5–1 Hz) as well as slow oscillation density before the onset of somnambulistic episodes versus non-behavioral awakenings recorded from the same group of sleepwalkers. A secondary aim was to describe the time course of observed changes in slow-wave activity and slow oscillations during the 3 min immediately preceding the occurrence of somnambulistic episodes.MethodsTwelve adult sleepwalkers were investigated polysomnographically during the course of one night.ResultsSlow-wave activity and slow oscillation density were significantly greater prior to patients' somnambulistic episodes as compared with non-behavioral awakenings. However, there was no evidence for a gradual increase over the 3 min preceding the episodes.ConclusionsIncreased slow-wave activity and slow oscillation density appear to be specific to sleepwalking episodes rather than generalized to all sleep–wake transitions in sleepwalkers.