Sleep and non-motor symptoms in Parkinson's disease

Beyond the cardinal motor symptoms, bradykinesia, rigidity, tremor and postural instability, defining the diagnosis of Parkinson's disease, there is a big spectrum of non-motor features that patients may suffer from and that may reduce their quality of life. Non-motor symptoms are not only frequent but also often under-reported by patients and caregivers. As they are frequently under-recognized by clinicians, they remain consequently under-treated. This review wants to give a short overview of the importance of non-motor symptoms on patients' quality of life and helpful assessment tools that might facilitate recognition of non-motor features during clinical setting. Given the wide range of non-motor symptoms in Parkinson's disease, we concentrate on common issues such as depression and sleep disorders like sleep-onset insomnia or sleep maintenance insomnia and restless legs syndrome. Thereby, we present some recent studies that have investigated the efficacy of dopaminergic drugs, especially dopamine agonists, revealing possible treatment strategies and thus improving disease management.