Mixed states, where both manic or hypomanic symptoms and depressive symptoms occur at the same time, also occur frequently with bipolar I patients (for example, depression with the racing thoughts of mania).
Cyclothymia refers to the cycling of hypomanic episodes with depression that does not reach major depressive proportions.
Although many clinicians find the criteria too rigid, a hypomanic diagnosis requires a duration of at least four days with at least three of the symptoms indicated for manic episodes (four if mood is irritable and not elevated).
In addition, because hypomanic episodes are characterized by high energy and goal-directed activities and often result in a positive outcome or are perceived in a positive manner by the patient, bipolar II disorder can go undiagnosed.