How to evaluate sleepiness in Parkinson’s disease?

Abstract

background: Excessive daytime sleepiness is a frequent complaint in Parkinson’s disease; however its determinants remain unclear. Objective: To assess the frequency and the determinants of subjective and objective sleepiness in patients with Parkinson’s disease compared to controls. One hundred and thirty-four consecutive patients with Parkinson’s disease, without selection bias for sleep complaint, and 34 controls underwent a semi-structured clinical interview and a one night of polysomnography followed by a multiple sleep latency test. Subjective sleepiness was defined as an Epworth sleepiness scale score over ten and objective sleepiness as mean sleep latency on multiple sleep latency test lower than eight minutes. Demographic and clinical data, treatment, pain, depressive symptoms, the presence of insomnia, restless legs syndrome, REM sleep behaviour disorder, and nighttime sleep measures were collected for all participants to control for confounding variables. Among 134 patients with Parkinson’s disease, 62 (46.3%) had subjective and 18 (13.4%) had objective sleepiness. None of the patients presented several sleep onset REM periods on the multiple sleep latency test. Patients with Parkinson’s disease had higher frequency of restless legs syndrome, REM sleep behaviour disorder, depressive and insomnia symptoms than controls. Patients had longer REM sleep latency and N3 sleep duration, shorter REM sleep duration and higher periodic leg movements during sleep and micro arousals indexes compared to controls but less apnea/hypopnea events. In patients with Parkinson’s disease, a higher body mass index was associated with subjective and objective excessive daytime sleepiness. After adjustment for body mass index, pain complaint and mean daytime sleep latency were associated with subjective sleepiness, and a higher apnea/hypopnea index with objective sleepiness. A weak correlation was found between Epworth sleepiness scale and multiple sleep latency test. No between group-differences were found for depressive symptoms, sleep complaints, disease severity, treatment, and sleep parameters except apnea/hypopnea index. The complaint of sleepiness is frequent in Parkinson’s disease in contrast to objective sleepiness assessed by neurophysiological measure. New determinants for excessive daytime sleepiness were identified with pain for subjective sleepiness, sleep-disordered breathing for objective sleepiness and being overweight/obese for both subjective and objective sleepiness. As the sensitivity of multiple sleep latency test to identify Parkinson’s disease patients with disabling sleepiness remained questionable further studies are required to validate the best methods to screen and objective hypersomnia in Parkinson’s disease to propose wake promoting treatments and to prevent car accidents. To all the patients who participated to the study.