Clinical features associated with sleep disturbances in Parkinson's disease

Sleep disturbances, such as REM sleep behavior disorder (RBD) and excessive daytime sleepiness, are more common in patients with Parkinson's disease (PD) than in the general population. Apart from that, their relation to PD seems to diverge considerably. Our aim was to explore the frequency and associated motor- and non-motor features of sleep related symptoms in PD.

One hundred and seven patients with PD, 65 men and 42 women, were included in a cross-sectional study. Excessive daytime sleepiness was examined by the Epworth sleepiness scale. Probable RBD (pRBD) was diagnosed by the validated REM sleep behavior disorder screening questionnaire. Further sleep symptoms were explored by the Parkinson's disease sleep scale. Motor- and non-motor symptoms were assessed and compared in patients with and without pRBD and excessive daytime sleepiness, respectively.

pRBD was present in 38% and excessive daytime sleepiness was present in 29% of the patients. As opposed to excessive daytime sleepiness, pRBD showed no association to disease duration or severity. PD patients with pRBD reported more cognitive problems. There was a trend towards more autonomic dysfunction in patients with pRBD. Nocturia and sleep fragmentation were the most frequent general sleep problems reported by the patients.

Our results suggest that excessive daytime sleepiness is related to disease duration, and possibly caused by progressive neurodegeneration. pRBD seems to be a distinct feature present in only a proportion of PD patients.