People with bipolar disorder experience unusually intense emotional states that occur in distinct periods called "mood episodes." Each mood episode represents a drastic change from a person’s usual mood and behavior. An overly joyful or overexcited state is called a manic episode, and an extremely sad or hopeless state is called a depressive episode. Sometimes, a mood episode includes symptoms of both mania and depression. This is called a mixed state. People with bipolar disorder also may be explosive and irritable during a mood episode.
Extreme changes in energy, activity, sleep, and behavior go along with these changes in mood. Symptoms of bipolar disorder are described below.