Bipolar disorder is a brain disorder that causes severe shifts in mood, energy and activity level, notes the National Institute of Mental Health. Bipolar disorder affects the ability to function and carry out daily tasks. Bipolar disorder may cause problems in relationships and sustaining employment.
Bipolar disorder is treated successfully with medications such as mood stabilizers, antipsychotics and antidepressants, according to the National Institute of Mental Health. Some symptoms of bipolar disorder when a person is in a manic state include talking very fast, having racing thoughts and sleeping very little. Symptoms of a depressive episode include feeling sad or hopeless, being overly tired and thinking of death or suicide.