Sleep disturbances are common early after major surgery, and are associated with delayed recovery. A previous study showed that dexmedetomidine-esketamine combination as a supplement to patient-controlled intravenous analgesia improved postoperative analgesia and subjective sleep quality in patients after scoliosis correction surgery. The purpose of this trial is to test the hypothesis that dexmedetomidine-esketamine combination used as a supplement during general anesthesia and postoperative intravenous analgesia may reduce sleep disturbances in adult after major noncardiac surgery.