Postoperative Melatonin Administration and Delirium Prevention in Patients Undergoing Vascular and Cardiac Surgery

The investigators plan to evaluate the effect of postoperative melatonin administration on postoperative delirium in patients undergoing vascular and cardiac surgery. A total of 302 patients older than 60, undergoing elective vascular surgery will be randomly divided into 2 groups: treatment and control. During the first 5 postoperative days patients will receive sublingually either melatonin 5 mg or placebo at 9:00 pm. The patients will be assessed for the signs of delirium, quality of sleep and severity of pain daily for the first postoperative week. Screening of delirium will be performed by the specially trained research assistant and based on the Confusion Assessment Method and the validated chart review. Diagnosis of delirium will be confirmed by the psychiatrist. Incidence of delirium will be compared between the groups.