Development of daytime somnolence over time in Parkinson's disease.

The authors examined the development over time of excessive daytime sleepiness (EDS) in patients with PD by evaluating EDS among 142 patients in 1993 and 4 years later. Eleven patients were diagnosed with EDS in 1993. In all of these patients, EDS persisted 4 years later. During follow-up, 30 new patients had EDS (6% new patients per year). In 1997, 29% of the patients with PD had EDS. The development of EDS correlated with more advanced disease and dementia.