Objective: This study aims to systematically quantify the impact of melatonin on sleep quality and daytime sleepiness in individuals diagnosed with Parkinson’s disease (PD).

Background: Sleep disturbances are prevalent in Parkinson’s disease (PD) and significantly impact quality of life. Melatonin, a crucial modulator of circadian rhythms, has been investigated for its potential to enhance sleep quality and alleviate daytime sleepiness in PD. However, the existing evidence remains inconclusive, largely due to dosage, formulation, and treatment duration inconsistencies.

Method: A thorough search of PubMed, Cochrane, Scopus, and Web of Science was performed to find related RCTs. The quality of the trials was assessed using the ROB-2 tool. Primary outcomes included pooled mean differences in Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS) scores. Heterogeneity was evaluated using Chi-square and I² statistics, and subgroup analyses included treatment duration (> 4 vs. ≤ 4 weeks), dosage (≤ 4 vs. > 4 mg), and formulation (immediate-release vs. prolonged-release).

Results: Five RCTs were included in the analysis. Melatonin at doses ≤ 4 mg showed no significant improvement in total PSQI scores (MD = -1.26, 95% CI: -2.72 to 0.20, I² = 58%, P = 0.09), though excluding Gilat et al study shifted results to significance (MD = -1.74, 95% CI: -2.63 to -0.85, I² = 0%, P = 0.0001). Higher doses (>4 mg) showed a significant effect (MD = -2.90, 95% CI: -4.02 to -1.78, P < 0.00001). Short-term use (≤ 4 weeks) significantly improved PSQI scores (MD = -2.43, 95% CI: -3.98 to -0.88, I² = 0%, P = 0.002), whereas longer durations (>4 weeks) showed no significant effect (MD = -1.24, 95% CI: -3.15 to 0.67, I² = 83%, P = 0.2). Immediate-release melatonin significantly improved PSQI scores (MD = -2.20, 95% CI: -3.32 to -1.08, I² = 45%, P = 0.0001), while the prolonged-release formulation showed no significant effect (MD = -0.61, 95% CI: -4.15 to 2.93, I² = 83%, P = 0.74). Regarding ESS score, Melatonin significantly reduced the total ESS score compared to placebo (MD [95% CI] = -0.97 [-1.81, -0.14, I2 = 12%, overall effect; P =0.02)

Conclusion: Our findings suggest that melatonin may improve sleep quality and decrease daytime sleepiness in individuals with Parkinson’s disease, especially when using immediate-release formulations over the short term.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-effect-of-melatonin-on-sleep-quality-and-daytime-sleepiness-in-parkinsons-disease-a-systematic-review-and-meta-analysis-of-randomized-placebo-controlled-trials/