Sleep disturbances usually develop in elderly patients after major surgery, which are manifested as prolonged sleep latencies, shortened sleep duration, frequent wake-up, disordered circadian rhythm, abnormally increased stages 1 and 2 non-rapid eye movement (N1 and N2) sleep, and decreased or absent slow wave sleep (SWS) and rapid eye movement (REM) sleep. Occurrence of sleep disturbances is harmful for the recovery of both physiological and mental functions after surgery, and may even lead to the development of postoperative complications. For example, study showed that postoperative sleep disturbances were associated with increase risks of delirium, cardiovascular events and infections, prolonged durations of stay in ICU and hospital, increased medical expenses and high mortality rate. However, methods that may effectively improve the quality of postoperative sleep are still lacking.