L-DOPA-induced excessive daytime sleepiness in PD: a placebo-controlled case with MSLT assessment.

A 74-year-old patient with idiopathic Parkinson's disease was evaluated for unintended sleep episodes that occurred after long-term treatment with 400 mg/day of L-dopa. Overnight sleep studies and multiple sleep latency testing were carried out under double-blind administration of either L-dopa or placebo. Mean sleep latency with L-dopa was 7 minutes, in contrast to a normal value of 19 minutes, 25 seconds with placebo. The authors' results suggest that L-dopa may cause daytime somnolence in some patients with Parkinson's disease.