Correlates of excessive daytime sleepiness in Parkinson's disease.

Measures of excessive daytime sleepiness, neuropsychologic function, and mood were assessed in twenty-two persons with mid-stage Parkinson's disease (PD) and sixteen age-matched healthy controls. Levodopa dose equivalents (LDE) were computed for the patients. While Epworth sleepiness score (ESS), Mini Mental State Exam, logical memory, Stroop, and the mood scales, reliably distinguished patients from controls, only the mood scales (especially anxiety) were reliably associated with ESS. LDE was not significantly associated with ESS. Excessive daytime sleepiness in patients with mid-stage PD may be more strongly related to anxiety than to other neuropsychologic dysfunction or dopaminergic dosing levels.