Self-awareness (insight), also known as perception or introspection, refers to the patient’s ability to recognize and judge his or her own mental state. The degree of impairment of self-awareness varies among mental illnesses. Patients with “mild” mental disorders generally have intact self-awareness, meaning that they are able to recognize their abnormal mental activity and actively seek medical help for this distress. Patients with “severe” mental disorders generally lack self-awareness, i.e., they cannot recognize their own pathological manifestations, deny the existence of mental problems, and believe that their hallucinations, delusions, and other psychopathological symptoms are objective reality, so they often refuse to seek medical treatment. Lack of self-knowledge is an important sign of severe mental disorder, and the presence or absence of self-knowledge and the degree of recovery of self-knowledge are often used as important indicators to determine the severity of the disease and the degree of improvement of the disease. Full recovery of self-knowledge is one of the important indicators of recovery from mental illness. Clinically, self-knowledge is closely related to the patient’s initiative to seek medical treatment, as well as the compliance with treatment, and subsequently to the patient’s clinical outcome and results.