Daytime sleepiness and alertness in patients with Parkinson disease.

STUDY OBJECTIVES: The goal of the study was to objectively measure daytime sleepiness and alertness in patients undergoing treatment for idiopathic Parkinson disease (PD) and assess potential contributing factors. DESIGN: Prospective study. SETTING: An accredited sleep disorders center in a university-based medical center in a large urban area. PATIENTS: Twenty consecutive subjects with idiopathic PD were recruited from a tertiary-care movement disorders clinic. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Patients underwent polysomnography, with a Multiple Sleep Latency Test (MSLT) and a Maintenance of Wakefulness Test (MWT) on the following day. Forty-seven percent of the sample was pathologically sleepy according to the MSLT, but only 26% had abnormal MWT scores. There was also a different pattern of correlations between predictors of sleepiness and MSLT and MWT scores. Percentage of stage 1 sleep had the largest correlation with MSLT (-0.42), while pergolide equivalents had the largest correlation with MWT (-0.70). CONCLUSIONS: In this sample of subjects with PD, severe daytime sleepiness was common and was related to poor sleep quality. Daytime alertness as measured by the MWT was impaired as medication burden increased.