The effect of melatonin on sleep quality and daytime sleepiness in Parkinson's disease: A systematic review and meta-analysis of randomized placebo-controlled trials.

BACKGROUND

Sleep disturbances are common in Parkinson's disease (PD), significantly impacting quality of life. Melatonin may help, but evidence regarding dosage, formulation, and treatment duration remains inconclusive.

OBJECTIVE

To quantitatively analyze the effect of melatonin on sleep quality and daytime sleepiness in patients with PD.

METHODS

We comprehensively searched multiple databases up to February 2025, selecting relevant randomized controlled trials (RCTs). RevMan software was used for analysis. Subgroup analyses included treatment duration (4 weeks vs. 8-12 weeks), dose (≤4 mg vs. >4 mg), and formulation (immediate-release vs. prolonged-release).

RESULTS

Five RCTs (206 patients) were included. Doses ≤4 mg showed no significant improvement in total Pittsburgh Sleep Quality Index (PSQI) scores (MD = -1.26, 95 % CI: -2.72 to 0.20). Doses >4 mg demonstrated a stronger effect (MD = -2.90, 95 % CI: -4.02 to -1.78). Short-term use (4 weeks) significantly improved PSQI scores (MD = -2.43, 95 % CI: -3.98 to -0.88), whereas longer treatment (8-12 weeks) showed a non-significant effect (MD = -1.24, 95 % CI: -3.15 to 0.67). Immediate-release formulations significantly improved PSQI scores (MD = -2.20, 95 % CI: -3.32 to -1.08), while prolonged-release formulations showed no significant effect (MD = -0.61, 95 % CI: -4.15 to 2.93). Melatonin modestly reduced excessive daytime sleepiness measured by the Epworth Sleepiness Scale (ESS) (MD: -0.97, 95 % CI: -1.81, -0.14).

CONCLUSION

Melatonin may improve sleep quality and reduce daytime sleepiness in PD patients, particularly with short-term use of immediate-release formulations.