A mixed episode is not a disorder, but rather a part of a mental disorder, most commonly bipolar disorder. It consists of meeting the criteria for both a manic episode as well as a major depressive episode nearly every day for at least a full week.

Like all mental disorders, the disturbance must be severe enough to cause distress or impairment in social, occupational, education or other important functioning and is not better accounted for by the physiological effects of substance use or abuse (alcohol, drugs, medications) or a general medical condition.