Bipolar disorder is a serious mental illness characterized by episodes, or cycles, of mania and depression. A few of the symptoms that can occur during the manic episodes of a person with bipolar disorder include overly inflated self-esteem, increased talkativeness, and racing thoughts. Among the symptoms that someone with bipolar disorder may experience during his or her depressive episodes are loss of energy, physical slowing or agitation, and loss of interest or pleasure in activities that were once enjoyed. If left untreated, the condition usually becomes worse. However, the good news is that people with bipolar disorder can usually lead healthy and productive lives when the illness is effectively treated.