Bipolar disorder (BD) is the most dangerous mental illness, with the highest suicide rate among various mental illnesses. Light therapy (LT) is a novel and effective therapy for BD. In this article, the physiological mechanisms and current clinical applications of LT in the treatment of BD are reviewed. LT transmits light signals through the inherent photosensitive retinal ganglion cells on the retina to areas such as the anterior chiasmatic nucleus of the hypothalamus, promoting their regulatory functions concerning circadian rhythm, endocrine, and neurotransmitters, thereby relieving BD depression. The mainstream view is that both single LT and LT combination therapy can significantly reduce the severity of depression in BD. With good safety of LT treatment for BD, both strong and weak light treatments are suitable for BD patients. Currently, research mainly adopts white light treatment, with a course of 1~8 weeks. Further research on LT clinical parameters (such as intensity, spectrum, and daily exposure duration) is still needed to provide reference for clinical practice.

bipolar disorder  /  light therapy  /  depressive state  /  biological rhythm  /  melatonin  /  neurotransmitter