major depressive episode
a period in which an individual experiences anhedonia or is persistently sad, pessimistic, or otherwise overly negative. Additional symptoms include poor or increased appetite with significant weight loss or gain; insomnia or excessive sleep; psychomotor agitation or psychomotor retardation; loss of energy with fatigue; feelings of worthlessness or inappropriate guilt; reduced ability to concentrate or make decisions; and recurrent thoughts of death, suicidal ideation, or attempted suicide. DSM–5 retains these same symptomatic criteria but has removed its predecessor’s qualified exclusion of bereavement with respect to major depressive episode and replaced it with a broader advisory (see bereavement exclusion). One or more major depressive episodes are a characteristic feature of major depressive disorder and bipolar disorder.