In cyclothymic disorder, periods of hypomania alternate with depression. In most cases of bipolar disorder, the depressive phases far outnumber manic phases, and the cycles of mania and depression are neither regular or predictable. Many patients, in fact, experience states of both mania and depression, called mixed mania or mixed state. The usual pattern of bipolar disorder is one of increasing intensity and duration of symptoms that progresses slowly over many years. Patients with the disease, however, may experience symptoms in very different ways.
Bipolar disorder can be severe and long-term, or it can be mild with infrequent episodes.
A bipolar patient averages 8 to 10 manic or depressive episodes over a lifetime, but some people experience more severe symptoms. The symptoms of depression experienced in bipolar disorder are almost identical to those of major depression. Depressive symptoms in bipolar patients also tend to be atypical, i.e., one sees an increase in sleep and appetite, a feeling of heaviness in the body, a tendency to feel rejected, and a preservation of volatile mood. One interesting study reported that many bipolar patients experienced dreams of death at the low point of their depression, and these dreams were soon followed by an upward mood change. Untreated pure mania can last three to six months.