Melatonin for rapid eye movement sleep behavior disorder in Parkinson's disease: A randomised controlled trial.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 31674060 · doi:10.1002/mds.27886
What was done
Randomized, double-blind, placebo-controlled, parallel-group trial in 30 Parkinson's disease patients with rapid eye movement sleep behavior disorder (RBD). Participants were assigned to receive 4 mg oral prolonged-release melatonin once daily before bedtime or matched placebo (n = 15 per group) for 8 weeks, with 4-week observation periods pre- and post-intervention. The primary outcome was the aggregate number of RBD incidents per week averaged over weeks 5 to 8 of treatment recorded in weekly diaries and evaluated by mixed-model ANOVA.
What was found
No significant difference occurred between groups at the primary endpoint: 3.4 events/week in the melatonin group versus 3.6 events/week in the placebo group (difference: 0.2; 95% CI: -3.2 to 3.6; P = 0.92). Mild adverse events (headaches, fatigue, morning sleepiness) occurred in 4 patients taking melatonin and 5 taking placebo.
Why it matters
Despite widespread clinical interest in melatonin for sleep disturbances in Parkinson's disease, this randomized trial found no evidence that 4 mg of prolonged-release melatonin reduces RBD episode frequency.
Limits
The sample size was very small (n = 30 total, 15 per arm), leaving wide confidence intervals that limit definitive conclusions. Only one dosage (4 mg) of a prolonged-release formulation was evaluated over a short 8-week duration, and outcomes relied on subjective diary reporting rather than objective polysomnography.
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