Melatonin Does Not Improve Sleep Quality in a Randomized Placebo-controlled Trial After Primary Total Joint Arthroplasty

Introduction: Sleep disturbance is a common concern among patients who have undergone total joint arthroplasty (TJA). Poor sleep during the postoperative period affect quality of life directly and may influence pain recovery after TJA. The purpose of this prospective study was to investigate whether the daily use of exogenous melatonin for 6 weeks after TJA can mitigate the effects of TJA on sleep. Methods: A cohort of 118 patients undergoing primary total hip arthroplasty or total knee arthroplasty from 2018 to 2020 were randomized to melatonin (6 mg) or placebo for 42 days after surgery. Inclusion criterion was patients undergoing unilateral primary TJA. Patients who underwent bilateral TJA and revision TJA, with a history of sleep disturbance, and on opioid medication or sleep aids preoperatively were excluded. Sleep quality was assessed at baseline and at 2 and 6 weeks postoperatively using the validated self-administered questionnaire, Pittsburgh Sleep Quality Index (PSQI). Continuous and categorical variables were analyzed using Student t-test and chi-square analysis, respectively. Multivariate linear regression analysis was also conducted. Results: Patients in both groups exhibited higher PSQI scores, representing lower sleep quality, at both 2 and 6 weeks postoperatively compared with that at baseline. Overall, global PSQI scores were 6.8, 9.8, and 8.8 at baseline, week 2, and week 6, respectively. No significant differences were noted between melatonin and placebo groups at baseline (6.8 versus 6.8, P = 0.988), week 2 (10.2 versus 9.3, P = 0.309), or week 6 (8.8 versus 8.7, P = 0.928). In multivariable regression, the only significant predictors of increased PSQI scores were an elevated baseline PSQI score (at both time points), a decreased length of stay (at week 2 only), and patients undergoing total hip arthroplasty versus total knee arthroplasty (at week 6 only). Conclusion: Patients undergoing TJA had poor sleep quality both preoperatively and postoperatively. The use of exogenous melatonin did not demonstrate any notable effect on sleep quality.