Inclusion Criteria:  Patients undergoing nephrectomy under general anesthesia aged from 20 to 60 years. ASA 1 or 2. BMI 25 to 30  Exclusion Criteria:  Patients with uncontrolled hypertension. Patients presenting with (IHD, significant arrhythmias, heart failure). Allergy to melatonin. History of epileptic seizures, psychoactive medications, neurological disorders or trauma.