• Sleep electroencephalograms were studied in 13 patients with panic disorder, six of whom experienced panic from sleep, and seven controls. Sleep was disturbed in the patients, as manifested by increased sleep latency, decreased sleep time, and decreased sleep efficiency. Rapid eye movement (REM) latencies were not reduced in the patient group. All six of the panic awakenings were preceded by non-REM sleep, which could be further characterized as a transition from stage II toward delta sleep. The overall degree of sleep disturbance (ie, sleep latency, sleep efficiency) did not appear to be influenced by the occurrence of sleep panic. There was also an association of increased REM latency with nights of sleep panic.