Nighttime sleep problems and daytime sleepiness in Parkinson's disease.

Our objective is to evaluate nighttime sleep problems (NSP) and daytime sleepiness (DS) in patients with Parkinson's disease (PD) compared to controls, and to assess relations with demographic, disease-related, and clinical characteristics in patients. NSP and DS were evaluated with the SCOPA-SLEEP questionnaire in PD patients and controls. In patients, other disease-related and clinical characteristics were also evaluated. Four hundred twenty PD patients [mean (SD) age 61.1 (11.5) years] and 150 controls [mean (SD) age 60.9 (9.9) years] participated in the study. Compared to controls, a significantly greater proportion of patients had excessive DS (EDS) (43 vs. 10%), excessive NSP (ENSP) (27 vs. 9%), or used sleep medication (17 vs. 12%). Difficulties with falling asleep were similar in both groups. In both patients and controls, women experienced more NSP than men. In patients, depressive symptoms accounted for 21% of NSP variance and was the major contributor to the total explained variance (30%). Furthermore, NSP were related to dopamine-agonist and levodopa dose, whereas DS was related to age, dopamine-agonist dose, and disease severity. NSP and DS occur frequently in PD, with EDS being reported more commonly than ENSP. No strong relations were found between DS and demographic or clinical variables. The strong relation between NSP and depressive symptoms in PD calls for future studies to explore the nature of this relation.