Movement/arousal has been described as a characteristic of adult obstructive sleep apnea syndrome (OSAS), but opinions differ as to whether or not OSAS in children increases the frequency of movement/arousal. The problem that we decided to address was the lack of a comprehensive definition and characterization of movement/arousals in children. We therefore quantified and classified movement/arousals during nocturnal polysomnography in 15 children 5.2 +/- 2.7 SD yr of age being evaluated for OSAS. Movement/arousals were defined by modifying the standard criteria for scoring arousals in adults. Median respiratory disturbance index was 4.4/h, with a range of 1 to 28/h. Videotape review was required to adequately distinguish technician-induced from spontaneous movement/arousals. Although movement/arousal durations varied from 1 s to prolonged awakenings, a high frequency of brief, 1- to 3-s movement/arousals occurred in all classification categories: respiratory, 44%; technician-induced, 33%; spontaneous, 36%. When comparing a 16-channel PSG montage with that of a seven-channel cardiorespiratory montage, we found that 84% of all movement/arousals could be detected using the abbreviated montage. In conclusion, we propose a simple classification system that distinguishes three types of movement/arousals: respiratory, technician-induced, and spontaneous. Our results further suggest that a simple montage using cardiorespiratory channels and videotaping would be suitable for home study and sensitive for identifying movement/arousals.