Classic symptoms of mania include persistent elevation of mood coupled with lability (ups and downs) and irritability, high energy, decreased need for sleep, the sensation that one's thoughts are racing, rapid speech, and impulsive, risky behavior. Mania can start abruptly, with the development of symptoms occurring and escalating over several days. Alternatively, mania can develop more gradually, with symptoms developing over a period of a few weeks. The initial state of well-being in patients changes to irritability, grandiosity and, in some cases, false beliefs of extraordinary powers. The manic person can furthermore engage in very high-risk behaviors: activities such as exorbitant spending, impulsive sexual behavior and drug use are typical.

Some drugs can trigger or mimic the state of mania. Amphetamines, antidepressants, cocaine, and corticosteroids are some of these drugs. Also some medical conditions, such as hyperthyroidism and multiple sclerosis, can present and masquerade as mania. When a manic patient is evaluated, part of the essential diagnostic evaluation is to ascertain if there is a specific cause; e.g., if the patient is under the influence of drugs or has an exacerbation of a known medical condition. If a causative agent is not found, the diagnosis of bipolar disorder is then explored.

The manic period of bipolar disorder can last from days to months. The depressive episodes tend to be longer, ranging from weeks to months. The period between manic and depressive episodes can vary: it may be months or even years. Predicting when a recurrence will happen is difficult. The best clue is to review past patterns of episodes. Also, a family history of bipolar disorder may be indicative of more recurrences.

It is not known why people get bipolar disorder, although several observations about its occurrence have been noted. First, it tends to run in families, and the more people in a family with bipolar disorder, the greater the chance of another family member expressing the illness. These observations lend a genetic component to bipolar disorder. Second, studies of brain function show that there could be a disturbance of certain neurotransmitters. While many neurotransmitters have been implicated in bipolar disorder, there is presently no clear consensus on how their interaction causes the condition. And, third, stressful events predispose people to having bipolar episodes. A person under stress, for example, might use a drug that could cause him or her to forgo sleep, thus prompting a manic episode.

There are many different, successful treatment options for patients with bipolar disorder. One of most important interventions is education. A patient who has the insight to recognize the first symptoms of mania or depression is more apt to seek treatment, which is usually more successful when engaged at the onset of a manic or depressive episode.