Non-REM-sleep instability in recurrent sleepwalking in pre-pubertal children

BACKGROUND AND PURPOSE: We questioned whether or not the sleep of pre-pubertal children with recurrent sleepwalking was different from that recorded in normal children. PATIENTS AND METHODS: Twelve pre-pubertal chronic sleepwalkers were compared to age- and gender-matched normal children. All children had a clinical evaluation covering pediatric, sleep, neuropsychiatric and otolaryngological fields. Two standardized sleep questionnaires were administered, and a minimum of two successive polysomnograms were performed with monitoring of sleep electroencephalographic (EEG) and cardiorespiratory variables. The research investigations were performed on nights without sleepwalking to search for the presence of other sleep disorders, including upper airway resistance syndrome (UARS). Sleep was scored using standard atlases, but it was also evaluated for the cyclic alternating pattern (CAP) rate. RESULTS: All sleepwalkers presented with either obstructive sleep apnea (n=2) or UARS (n=10). Compared to normal children, sleepwalkers had shorter total sleep time but no significant change in wake after sleep onset when considering all arousals > 3 s. CAP analysis showed a significantly higher CAP rate than in controls. CONCLUSIONS: Chronic sleepwalkers have instability of non-rapid eye movement (NREM) sleep detectable only by the calculation of CAP rate. Instability of NREM sleep was seen even on nights without sleepwalking and is probably related to the presence of the associated sleep disorders. We hypothesize that chronic NREM-sleep instability is a risk factor for occurrence of sleepwalking when further sleep disruption is triggered by external events.