Does Melatonin Improve Sleep Following Primary Total Knee Arthroplasty? A Randomized, Double-Blind, Placebo-Controlled Trial.

Background: Sleep impairment following total knee arthroplasty (TKA) is common and may decrease patient satisfaction and recovery. Standardized postoperative recommendations for sleep disturbances have not been established. We aimed to assess whether melatonin use could promote healthy sleep and reduce sleep disturbance in the acute period following TKA.

Methods: Patients undergoing primary, elective TKA between July 19, 2021 and January 4, 2024 were prospectively enrolled and randomized to receive either 5 mg of melatonin nightly or placebo for 14 days postoperatively. Participants recorded their nightly pain on the visual analog scale, the number of hours slept, and the number of night-time awakenings in a sleep diary starting the night of surgery (postoperative day [POD] 0). Sleep disturbance was assessed preoperatively and on POD 14 using the patient-reported outcome measurement information system sleep disturbance form. Epworth Sleepiness Scores were collected on POD 14 to assess sleep quality.

Results: Of the 138 patients enrolled, 128 patients successfully completed the study protocol, with 64 patients in each group. Melatonin patients trended toward more hours of sleep on POD 2 (placebo: 5.0 ± 2.4, melatonin: 5.8 ± 2.0, P = .084), POD 3 (placebo: 5.6 ± 2.2, melatonin: 6.3 ± 2.0, P = .075), and averaged over POD 1 to 3 (placebo: 4.9 ± 2.0, melatonin: 5.6 ± 1.8, P = .073), although no differences were observed on POD 4 or after. Fewer night-time awakenings in the melatonin group were observed on POD 1 (placebo: 4.4 ± 3.9, melatonin: 3.6 ± 2.4, P = .197), although this was not statistically significant. Preoperative and postoperative Patient-Reported Outcomes Measurement Information System Sleep Disturbance score increases were comparable for both groups (placebo: 4.0 ± 8.4, melatonin: 4.6 ± 8.2, P = .894). The melatonin (65.4%) and placebo (65%) groups demonstrated similar rates of increased sleep disturbance.

Conclusions: Melatonin may promote longer sleep in the immediate postoperative period after TKA, although these benefits wane after POD 3. Disturbances in sleep should be expected for most patients, although melatonin may have an attenuating effect. Melatonin is safe and can be considered for TKA patients experiencing early sleep disturbances postoperatively.