Several lines of evidence suggest that a constellation of electroencephalogram (EEG) monitored sleep abnormalities exists in the vast majority of depressed patients. Disturbances of sleep during depressive episodes can include sleep maintenance difficulties, a delay in sleep onset, and a reduced amount of slow-wave sleep (Kupfer et al. 1984). Rapid eye movement (REM) sleep alterations during depressive episodes include a shortened first NREM period (which is usually referred to as a decrease in REM latency) and an increase in REM density during the first few hours of sleep, especially in the first REM period. The majority of these sleep abnormalities, whether they represent changes in REM or NREM sleep, are most pronounced during the first 100-120 min following sleep onset. creases in cortisol secretion rates (Linkowski et al. 1985), a flattening of the circadian rhythm in cortisol (Sachar 1976), and elevated cortisol nadir (Jarrett et al. 1983) have been reported and replicated in numerous investigations. The failure to suppress plasma cortisol in the Dexamethasone Suppression Test (DST) in many depressed patients has also supported the notion of a specific HPA abnormality (Carroll 1982).