Sleep disorders, a common concern in modern society, seriously affect people's physical and mental health. Reported findings suggest that both acute exercise intervention and long-term regular exercise intervention can improve the disrupted sleep structure and normalize the duration and proportion of the different phases of sleep. Moreover, exercise intervention has a positive effect on the endocrine functions, the metabolic functions, the immune response, the autonomic nervous system, and cardiac functions during sleep. It is a non-medicative therapeutic strategy for improving sleep disorders. The specific type of exercise intervention (aerobic exercise, resistance exercise, or meditative movement) adopted is one of the moderating variables of exercise intervention programs. Different types of exercise improve sleep disorders by way of different mechanisms. Exercise volume and intensity are another moderating variable of exercise intervention programs. The optimal amount and intensity of exercise for different individuals to improve sleep disorders may vary. Exercise interventions implemented at the different times throughout a day can also have varying degrees of impact on sleep disorders and there is no consensus on the optimal exercise time for improving sleep quality at present. Herein, we summarized the mechanisms by which exercise intervention improves sleep disorders from four perspectives, including epigenetics, hyperarousal, human circadian rhythm, and body temperature regulation. In addition, we discussed the current gaps and prospects of research in this field, aiming to provide a theoretical basis for the development of exercise prescriptions for sleep disorders.