In my daily work, I often have patients who visit me with insomnia. And, they tend to be more subjective in their complaints. Commonalities: having taken a variety of sleeping and other medications, resulting in unsatisfactory results; long treatment times; and repeated fluctuations in the condition. This often affects the patient’s health status; quality of life; work efficiency and many other aspects. In fact, sleep disorders are not only clinical surface phenomena, with the shift in the biomedical mechanism model, the etiology of sleep disorders? pathology have been newly explored. The past notion was that the relationship between sleep disorders and depression was a one-way causality, i.e., depression caused sleep disorders. New findings question this, suggesting that there is a complex bidirectional relationship between sleep disorders and depression, i.e., that sleep disorders are secondary to psychiatric disorders, and emphasizing the importance of treating psychiatric disorders rather than advocating treatment of coexisting sleep disorders. The fact that 90% of patients with major depressive disorder have sleep disorders also provides strong evidence for the relationship between sleep disorders and depression. With antidepressant treatment, sleep disturbances improve as well. This sheds new light on the mechanisms and treatment of the relationship between sleep disorders and depression. With a better understanding of the relationship between sleep disorders and depression, it is recommended that the entire treatment process should not only look at the clinical phenomenon of sleep disorders, but also focus on the risk of possible future psychiatric disorders and somatic disorders.