 Postoperative fatigue and sleep disturbances occur after minimally invasive surgery. The pathophysiological background is unknown, but several studies have shown disturbed melatonin secretion after surgery. It is unknown whether melatonin substitution will improve general wellbeing, fatigue or sleep disturbances after laparoscopic cholecystectomy. We set out to study in a randomized clinical trial to investigate the effect of 5 mg melatonin versus placebo, on postoperative sleep disturbances, fatigue and general wellbeing. 