Sleep and affective disorders. A minireview

The most predictable electroencephalographic sleep changes of major depression are a shortened first NREM sleep period, a prolonged first REM period (with increased density of rapid eye movements), sleep continuity disturbance, and diminished slow wave sleep (with shifting of delta activity from the first to the second NREM sleep period). The more rapid appearance of the first REM sleep period occurs in relation to sleep onset but not apparently in relation to clock time. The changes occurring in the first NREM-REM cycle of the night appear to be relatively specific to major (particularly endogenous) depression. Depressed men appear to have diminished nocturnal penile tumescence compared with healthy controls, but depressed patients generally do not have a higher incidence of sleep apnea or nocturnal myoclonus. The sleep physiologic changes of depression appear to persist into clinical remission, suggesting that they are trait-like. Published studies appear to support the conclusion that there is a close link between the regulation of sleep and the regulation of mood in affective illness.