Bipolar disorder is also called manic-depression. People with bipolar disorder experience mood swings from "high" episodes of mania to "low" periods of depression. When between these "highs" and "lows", people with BP often have the normal range of moods. In most cases, people with bipolar disorder experience more periods of depression than periods of mania. Bipolar disorder can be either severe or mild, and can have either frequent or infrequent mood swings. Depending upon their symptoms, bipolars are diagnosed as having bipolar I, bipolar II, or cyclothymic disorder.

Most people with bipolar I have episodes of both depression and mania. In very rare cases, they experience only mania. Bipolar I is distinguished from bipolar II by the severity and duration of the manic phase, which can last anywhere from a week to several months, and the experience of delusions. Risky behavior is common in manic episodes and patients often require hospitalization for their own safety.
The symptoms of mania can include rapid speech, insomnia, disconnected thoughts, grandiose ideas, hallucinations, extreme irritability, feelings of omnipotence, paranoia, violent behavior, a marked increase in strength, and openly promiscuous activity. (see Bipolar Screening)

Bipolar II and Hypomania

People with bipolar II suffer primarily from episodes of severe depression with occasional episode of "mild" mania, called hypomania. Hypomania differs from mania in that no delusions are experienced.
Like mania, hypomania can cause severely impaired functioning. The hypomanic episode often feels so good that bipolar patients often discontinue their medication in quest of a hypomanic episode. This is especially problematic because symptoms that come back after stopping drug treatment are often much harder to get back under control a second time.
While Bipolar II has sometimes been described as a "milder" form of bipolar disorder than Bipolar I, the suicide rate among people suffering form Bipolar II is actually higher than that for those suffering from Bipolar I.

Cyclothymic Disorder

People with cyclothymic disorder alternate between hypomania and mild depression. It is not as severe as bipolar I and II, but persists for longer periods with no break in symptoms. Cyclothymic disorder can later become full-blown bipolar disorder in some people, or can continue as a low-grade chronic condition.

Rapid Cycling

Most people with bipolar disorder have an average of 8 to 10 manic or depressive episodes over a lifetime. Some, however, experience much more severe symptoms called rapid cycling. They can swing (cycle) between "highs" and "lows" many times in one day. To be considered a rapid cycler, you must have at leat 4 mood swings in a year.

Mixed Episode

During a Mixed Episode, symptoms of both mania and depression occur at the same time. The excitability and agitation of mania is coupled with depression and irritability. This combination of high energy and agitation along with depression makes the mixed episode the most dangerous for risk of suicide.