Diagnosis of bipolar disorder II requires having at least one depressive episode and at least one hypomanic episode. In contrast to bipolar disorder I and mania, hypomania is instead an elevated mood that is not as chaotic nor strong, which also may not last as long either. Thus, bipolar disorder II can be confused for major depression. In fact, there is some debate as to whether this categorization should exist at all due to its similarities and lack of polar swinging.