People with bipolar disorder experience unusually intense emotional states that occur in distinct periods called "mood episodes." An overly joyful or overexcited state is called a manic episode, and an extremely sad or hopeless state is called a depressive episode.   While it is normal for everyone to go through ups and downs, it is the severity and duration of the mood related symptoms that determine the diagnosis of bipolar disorder.

Bipolar disorder, also known as manic-depressive illness, is a brain disorder that causes unusual shifts in mood, energy, activity levels, and the ability to carry out day-to-day tasks. These shifts are different from the normal ups and downs that everyone goes through from time to time and they may have nothing to do with what is going on in someone's life.