The Bipolar spectrum refers to a category of moo disorders that feature abnormally elevated mood. These disorders range from Bipolar I disorder, featuring full-blown manic episodes, to cyclothymia, featuring less prominent hypomanic episodes. These disorders may also present with depressive symptoms or episodes that alternate with the elevated mood states, or with mixed episodes that feature symptoms of both. The concept of the Bipolar spectrum is similar to that of Emil Kraepelin's original concept of Manic depressive illness.