Sleep disorders in Parkinson's disease

Sleep disorders in patients with Parkinson's disease (PD) are very common and have an immense negative impact on their quality of life. Insomnia, daytime sleepiness with sleep attacks, restless-legs syndrome (RLS) and REM-sleep behaviour disorder (RBD) are the most frequent sleep disorders in PD. Neurodegenerative processes within sleep regulatory brain circuitries, antiparkinsonian (e.g., levodopa and dopamine agonists) and concomitant medication (e.g., antidepressants) as well as comorbidities or other non-motor symptoms (such as depression) are discussed as causative factors. For the diagnosis of sleep disturbances we recommend regular screening using validated questionnaires such as the Pittsburgh Sleep Quality Index (PSQI) or the Medical Outcomes Study Sleep Scale (MOS), for evaluating daytime sleepiness we would suggest to use the Epworth Sleepiness Scale (ESS), the inappropriate sleep composite score (ISCS) or the Stanford sleepiness scale (SSS). All of these questionnaires should be used in combination with a detailed medical history focusing on common sleep disorders and medication. If necessary, patients should be referred to sleep specialists or sleep laboratories for further investigations. Management of sleep disorders in PD patients usually starts with optimization of (dopaminergic) antiparkinsonian therapy followed by specific treatment of the sleep disturbances. Aside from these clinical issues of sleep disorders in PD, the concept of REM-sleep behaviour disorder (RBD) as an early sign for emerging neurodegenerative diseases is of pivotal interest for future research on biomarkers and neuroprotective treatment strategies of neurodegenerative diseases, and particularly PD.