Evaluating the utility of melatonin in spine surgery: a systematic review and meta-analysis of randomized clinical trials.
BACKGROUND: Spine surgery is increasingly performed worldwide, and acute postoperative stressors such as pain and anxiety remain highly prevalent despite historical management with opioids and other pharmacological agents. Recently, interest has emerged in melatonin administration given its endogenous physiological roles, low cost, favorable adverse event profile, and documented benefits throughout surgical literature. PURPOSE: This study aims to consolidate the existing evidence on melatonin's utility specifically in spine surgery, an area not yet comprehensively evaluated, to inform clinical practice and enhance spine surgeon comprehension. STUDY DESIGN/SETTING: Preregistered on PROSPERO, this systematic review queried PubMed/MEDLINE, CINAHL, SPORTDiscus, and Web of Science on November 21st, 2025, for studies reporting outcomes following melatonin administration in patients undergoing spine surgery. METHODS: Study quality was assessed using the Cochrane Risk-of-Bias 2 tool. Extracted variables included demographics, comparator medications, dosages, and other relevant details. Statistical analyses included frequency-weighted means (FWMs), associated standard deviations, narrative syntheses, and limited meta-analyses, where appropriate. RESULTS: A total of 6 moderate-quality randomized trials were included from 749 screened. Melatonin (3-10 mg) was administered to 227 patients (FWM age=43.3±8.6 years; 46.2% male; BMI=26.6±3.2 kg/m2), placebo to 125 patients (age=43.2±10.1 years; 60% male; BMI=28.5±4.3 kg/m2), and active pharmacologic comparators (fentanyl, gabapentin, dexmedetomidine, zolpidem) to 151 patients (age=46.6±8.9 years; 40.5% male; BMI=26.3±3.5 kg/m2). Procedures primarily involved uncomplicated lumbar laminectomies (1-4 levels), with outcomes assessed up to 24 hours postoperatively. Melatonin was associated with significant improvements in early postoperative VAS-pain scores, blood-pressure-related, analgesic-related, and anxiety-related outcomes versus placebo across most reporting studies. Compared with active pharmacologic agents, significant benefits were observed only in select nausea- and anxiety-related instances. Limited meta-analysis (n=2) demonstrated higher 24-hour VAS-pain for melatonin versus gabapentin, though mean difference was near-negligible and harbored extensive statistical constraints. CONCLUSION: Melatonin demonstrates variable utility following spine surgery, with generally consistent anxiolysis and frequent benefit versus placebo but less consistent and comparatively weaker efficacy relative to active pharmacologic comparators. Future outcome-homogenous studies incorporating more granular, expansive comparator arms and more robust quantitative analyses are needed to further elucidate melatonin's role in advancing spine care. LEVEL OF EVIDENCE: Level II.