Bipolar disorder, previously known as manic depression, is a mental illness marked by periods of mania—where a person is in a chronically elevated or agitated state—alternating with, or sometimes mixed with, depression. The symptoms of the depressive period are the same as with major depression, except when a person is in what is known as a mixed affective episode. During a mixed episode, a person will have symptoms of mania at the same time as the depressive symptoms. During a depressive or mixed episode, people are at much greater risk of suicide.
The manic episodes can vary in duration and intensity. People who get more intense manic episodes are considered to have Bipolar I disorder. People with mild to moderate manic episodes, known as hypomania or cyclothymia, are considered to have Bipolar II.
In extreme cases, people experiencing a more severe manic episode may loose touch with reality and enter a psychotic state, where they have false, intense and unshakable believes beliefs (for instance a certainty that they alone can detect secret plots or intellectual concepts), and sometimes the perception that they have superhuman and almost god-like powers.