From National Institute of Mental Health (NIMH)

The National Institute of Mental Health (NIMH) is part of the National Institutes of Health (NIH), a component of the U.S. Department of Health and Human Services.

What is Bipolar Disorder?
Bipolar Disorder, also known as manic-depressive illness, is a serious medical illness that causes shifts in a persons mood, energy, and ability to function. Different from the normal ups and downs that everyone goes through, the symptoms of bipolar disorder are severe.

Signs Symptoms
Bipolar disorder causes dramatic mood swings from overly high and/or irritable to sad and hopeless, and then back again, often with periods of normal mood in between. Severe changes in energy and behavior go along with these changes in mood. The periods of highs and lows are called episodes of mania and depression.

Treatment
Most people with bipolar disorder can achieve substantial stabilization of their mood swings and related symptoms over time with proper treatment. A strategy that combines medication and psychosocial treatment is optimal for managing the disorder over time.