Types of depression
There are several forms of depressive disorders. The most common are major depressive disorder and dysthymic disorder.

Major depressive disorder, also called major depression, is characterized by a combination of symptoms that interfere with a person's ability to work, sleep, study, eat, and enjoy once–pleasurable activities. Major depression is disabling and prevents a person from functioning normally. An episode of major depression may occur only once in a person's lifetime, but more often, it recurs throughout a person's life.

Dysthymic disorder, also called dysthymia, is characterized by long–term (two years or longer) but less severe symptoms that may not disable a person but can prevent sufferers from functioning normally or feeling well. People with dysthymia may also experience one or more episodes of major depression during their lifetimes.