Bipolar disorders are conditions characterized by two extremes of mood: elation and depression. In a stereotypical presentation, the illness fluctuates from severe mania to profound depression and then back to mania.
Mania refers to a state of extreme excitement, hyperactivity, agitation, rapid speech, excessively high self-esteem, and excessive involvement in pleasurable activities that have a high potential for harmful consequences, such as extravagant spending and uncontrolled sexual behavior. It is also characterized by a decreased need for sleep and is often accompanied by disorganized thinking.
The term elation requires some clarification. It would be more accurate to refer to an excited mood state rather than simply an elevated or elated mood, since the subjective experience of a person experiencing mania may range from extreme euphoria to profound dysphoria.
The main syndromes included in the DSM-IV are Bipolar I Disorder and Bipolar II Disorder, which are differentiated based on the severity and duration of symptoms.
References:
Kaplan & Sadock: Synopsis of Psychiatry, twelfth edition
Kaplan & Sadock: Pocket Handbook of Clinical Psychiatry, fifth edition;
American Psychiatric Association: Diagnostic Manual of Mental Disorders, 1994;
Robert J. Waldinger: Psychiatry for Medical Students, third edition, translated by Anastas Suli.