Nocturnal Hypokinesia and Sleep Quality in Parkinson's Disease

Objectives To study the relationship between nocturnal hypokinesia and sleep quality in Parkinson's disease (PD). Design Questionnaire study using intergroup analysis. Setting Parkinson Centre Nijmegen, a tertiary university referral center. Participants Two hundred forty individuals with Parkinson's disease. Measurements Clinical and demographic data were obtained. Nocturnal hypokinesia was assessed using Question 35 of the Parkinson's Disease Quality of Life Questionnaire and rated on a 5-point Likert scale (1=all of the time to 5=never). The Pittsburgh Sleep Quality Index (PSQI) was used to quantify sleep quality, higher scores indicating poorer sleep quality. Results One hundred thirty-five of 240 participants had difficulties turning over in bed. Mean PSQI scores were significantly higher in participants with nocturnal hypokinesia (7.7 +/- 4.1) than in those without (6.1 +/- 3.4, P=.001). A regression model correcting for age, disease duration, and Hoehn and Yahr stage showed a significant influence of nocturnal hypokinesia on sleep quality (coefficient of determination=0.042, standardized-beta=0.163, P=.03). There was a linear relationship between frequency of nocturnal hypokinesia and sleep quality. Conclusion This is the first study that documents that nocturnal hypokinesia negatively affects sleep quality in PD. Nocturnal hypokinesia therefore merits therapeutic attention, including optimal nighttime dopaminergic treatment and education about turning strategies in bed.