Increased daytime sleepiness in Parkinson's disease: a questionnaire survey.

We evaluated the frequency and severity of excessive daytime sleepiness in an outpatient population with Parkinson's disease in comparison to age-matched controls and examined its relationship with antiparkinsonian drug therapy and sleep history. Increased daytime sleepiness and involuntary sleep episodes have been described in Parkinson's disease, but the etiology is not completely understood. The Epworth Sleepiness Scale (ESS), a validated questionnaire for daytime sleepiness, was prospectively administered to 99 consecutive outpatients with Parkinson's disease and 44 age-matched controls. In addition, a short sleep-screening questionnaire was used. The ESS revealed significantly increased daytime sleepiness in PD patients compared to controls (7.5 +/- 4.6 vs. 5.8 +/- 3.0, P = 0.013). The ESS score was abnormally high (10 or more) in 33 % of PD patients and 11.4% of controls (P = 0.001). ESS was not different between PD patients on levodopa monotherapy and those on levodopa and dopamine agonists, or between patients taking ergoline or non-ergoline dopamine agonists. In PD patients and in controls, sleepiness was significantly associated with reported heavy snoring. Increased daytime sleepiness is more frequent in patients with PD than in elderly controls. Similar to controls, increased daytime sleepiness in PD patients is correlated with heavy snoring.