This study examines the sleep architecture (polysomnography) of patients with panic disorder, social phobia, and depression, in comparison with that of normal controls. Continued analysis of such factors as movement time, REM latency, wakefulness after sleep onset, and sleep efficiency among the groups is an ongoing focus of research. The study of sleep panic attacks is a major focus of research for the Section. Evidence from the sleep laboratory continues to indicate that sleep panic attacks emerge from non-REM sleep -- typically either stage 2 or 3. On the nights when patients have had panic attacks, a prolonged REM latency has been noted, in contrast to the shortened REM latency of depression. End-tidal CO2 is being measured and measures of sleep apnea and nocturnal myoclonus are being employed. New methods of data analysis of sleep records are being developed such as recording number of K-complexes, spindles, and performing spectral analysis of data for between group comparisons. The Section is developing a methodology for quantifying vagal tone during sleep. Future studies will investigate the behavioral, biochemical, and neuroendocrine effects of chemical panicogenic agents administered during sleep in panic disorder patients and normal control subjects.