Exploring the role of melatonin in managing sleep and motor symptoms in Parkinson's disease: a pooled analysis of double-blinded randomized controlled trials.

BACKGROUND

Parkinson's disease (PD), a progressive neurodegenerative disorder, often involves sleep disturbances, affecting 88-98% of patients. Melatonin, a sleep-regulating neurohormone, shows the potential to improve sleep quality and non-motor symptoms in PD.

AIM: To evaluate melatonin's efficacy and safety in PD patients with sleep disorders.

METHODS

We systematically searched PubMed, Scopus, Web of Science, and Cochrane till January 2025. The risk of bias in the included studies was evaluated using the Cochrane risk-of-bias tool. Dichotomous outcomes were expressed as risk ratios (RRs) with 95% confidence intervals (CIs), while continuous outcomes were reported as mean differences (MDs) with 95% CIs.

RESULTS

We retrieved 2537 records. Five double-blinded RCTs were finally included. The meta-analysis revealed a significant improvement in sleep quality, as measured by the Pittsburgh Sleep Quality Index (PSQI), in the melatonin group compared to placebo (MD= -1.88, 95% CI: [-3.07, -0.68], P = 0.002). However, no significant differences were observed for the Epworth Sleepiness Scale (MD= -1.04 CI: [-2.81, 0.73], P = 0.25), total sleep time (MD = 14.85 min CI: [-5.45, 35.16], P = 0.15), sleep efficiency, sleep latency, REM sleep latency, frequency of arousals, or REM Sleep Behavior Disorder Screening Questionnaire (RBDSQ; MD = 0.74, P = 0.50). For Parkinson's disease-related outcomes, melatonin significantly improved Non-Motor Symptom Scale (NMSS) scores but showed no significant effects on UPDRS Part III scores or Parkinson's Disease Quality of Life.

CONCLUSION

Melatonin improves subjective sleep quality and non-motor symptoms in PD patients with a favorable safety profile, but effects on objective measures and motor symptoms remain inconclusive.

TRIAL REGISTRY NUMBER: This meta-analysis was registered on PROSPERO.

REGISTRATION NUMBER: CRD42024619496.