What are the three levels of bipolar?

There are four types of bipolar disorder:

* Bipolar I disorder is characterized by at least one manic or mixed episode. A manic episode is a period of abnormally elevated or irritable mood, increased energy, and decreased need for sleep. A mixed episode is a period of symptoms of both mania and depression.

* Bipolar II disorder is characterized by at least one major depressive episode and at least one hypomanic episode. A hypomanic episode is a period of elevated or irritable mood, increased energy, and decreased need for sleep that is less severe than a manic episode.

* Cyclothymic disorder is characterized by repeated periods of hypomanic symptoms and depressive symptoms that do not meet the criteria for a major depressive episode or a manic episode.

* Bipolar disorder not otherwise specified (BP-NOS) is used for cases that do not meet the criteria for any of the other bipolar disorder subtypes.