evaluating the potential effect of melatonin on the post-cardiac surgery sleep disorder

background : postoperative neurological injuries, including cognitive dysfunction, sleep disorder, delirium, and anxiety, are the important consequences of coronary artery bypass graft surgery (cabg). evidence has shown that postoperative sleep disturbance is partly due to disturbed melatonin secretion in the perioperative period. the aim of this study was to evaluate the effect of melatonin on postoperative sleep disorder in patients undergoing cabg. method: one hundred forty-five elective cabg patients participated in a randomized double-blind study during the preoperative period. the patients were randomized to receive either 3 mg of melatonin or 10 mg of oxazepam one hour before sleep time. each group received the medication from 3 days before surgery until the time of discharge. sleep quality was evaluated using the groningen sleep quality score (gsqs), and the incidence of delirium was evaluated by nursing records. sleep quality and anxiety scores were compared before and after surgery through the wilcoxon signed-rank test. the analysis of covariance (ancova) and independent t-test were used to compare the sleep and anxiety scores between the groups. p values ≤ 0.05 were considered statistically significant . results: totally, 137 patients at a mean age of 60 years completed the study (76% male). the analysis of the data showed that sleep was significantly disturbed after surgery in both groups. the patients in the oxazepam group demonstrated significantly higher disturbance in their mean postoperative gsqs score than did their counterparts in the melatonin group (p value < 0.001). a smaller proportion of the participants experienced delirium in the melatonin group (0.06%) than in the oxazepam group (0.12%); however, this difference was not statistically significant. conclusion: the result of the present study revealed that melatonin improved sleep in post-cardiac surgery patients more than what was observed with oxazepam. therefore, melatonin may be considered an effective alternative for benzodiazepines in the management of postoperative sleep disorder.