Sleep EEG in depression.

Depression is a common psychiatric disorder with sleep disturbance as a concomitant symptom. This paper selectively reviews the earlier, more global research and more recent studies with improved methodologies. Research has shown that EEG sleep changes (in particular, REM) can be used as an aid in differential diagnosis of depression and possibly as a way of treatment. It is speculated that an ultradian cycle disruption involving REM sleep mechanisms is related to primary depression.