A systematic study of electrophysiologic events [eight-channel EEG, electrocardiogram, electromyogram (EMGs)] surrounding 252 arousals from slow-wave sleep (SWS) in adults with sleepwalking (SW) and sleep terrors (ST) is reported. Hospital-based, overnight polysomnographic monitoring was conducted in 38 adults presenting to a sleep disorders center with injurious SW, ST (21 males, 17 females; mean age 29 years, range 17-69 years). Before nonbehavioral or behavioral arousals from SWS, neither EEG "delta wave buildup," nor heart rate (HR) acceleration, nor tonic/phasic EMG activation was identified. The postarousal EEG demonstrated three patterns: (a) diffuse, rhythmic, delta activity with a typical frequency of 2.2 Hz, a typical amplitude of 85 microV, and a typical duration of 20 s; (b) diffuse delta and theta activity intermixed with alpha and beta activity; and (c) prominent alpha and beta activity. Multichannel, high-voltage, delta activity was observed in <2% of all prearousal periods. HR acceleration emerged abruptly with SWS arousals, with significant changes in mean pre- versus postarousal HR (p < .001). Macrostructural sleep parameters ("sleep architecture") were intact. Therefore, our findings in adults with SW, ST strongly support the classification of SW/ST as disorders of (abrupt) arousal.