Bipolar disorder (also known as manic depression) is a mental illness characterized by extreme mood swings. A person suffering from this disorder has moods that go from elation to severe depression to violent anger. Energy level varies along with mood, from having lots of energy in the manic phase of the disease to lethargy during times of sadness and depression. Bipolar patients often lose touch with reality, plus, their sleep patterns, appetite, self-esteem, and relationships are all affected by the disease.