Everyone feels down at times, but long-term or severe symptoms may indicate a mood disorder, such as major depression which is also called clinical depression. Dysthymia is a less severe form. Bipolar disorder which was formerly known as manic depression involves alternating episodes of depression and mania. Postpartum depression occurs within a year of childbirth.

Although emotional symptoms have traditionally been used to detect depression, research shows that physical symptoms are also very common and should not be overlooked. The body has nerve pathways that determine how it handles pain sensations and emotions.