endogenous depression

noun Psychiatry.

1. a severe form of depression usually characterized by insomnia, weight loss, and inability to experience pleasure, thought to be of internal origin and not influenced by external events.

n.

1. A group of symptoms that resemble depression but are not precipitated by a stressful experience, especially psychomotor agitation or retardation, insomnia and early morning awakening, weight loss, excessive guilt, and lack of reactivity to one’s environment.