Bipolar disorder, also known as bipolar affective disorder, generally refers to a group of mood disorders in which there are both manic or hypomanic episodes and depressive episodes that meet the diagnostic criteria of symptomatology. Kraepelin (1898) first proposed that mania and depression belonged to the same disease unit, and considered alternating episodes of mania and depression as its main characteristics, and named it “bipolar disorder” (at present, many people still use this name). The American diagnostic system DSM, which has a great influence in the world, divides bipolar disorder into: bipolar I (at least one manic episode) and bipolar II (only light mania but no manic episode). Patients with only a history of manic episodes or a history of exact mild manic episodes (no history of depressive episodes) are also often included in bipolar disorder because they do not differ significantly from patients with a history of depressive episodes in terms of epidemiological data, treatment, etc. Goodwin et al. (1990) reported a 1% prevalence of bipolar I disorder, a 3% prevalence of bipolar I and II combined, and a 4% prevalence of cyclothymic disorder when combined with cyclothymic disorder. The 12-month prevalence of bipolar disorder was 2.6% and the lifetime prevalence was 3.9%. While bipolar disorder appears to be an episodic disorder, with many patients functioning well intermittently, it is in fact a chronic disorder, with most patients requiring long-term medication, even during intermittent periods. This is because numerous studies have shown that the chance of relapse increases significantly if treatment is intermittently interrupted. In addition, the treatment of bipolar disorder is complicated, and the treatment of the same patient in different periods, such as mania, depression, hypomania, and intermittent periods, can be very different.