The Link Between Sleep and Parkinson’s Disease

Sleep is more than just relaxation. It is a fundamental biological process with far-reaching effects on physical and mental health. But its complex relationship with disease remains poorly understood. Sleep disorders affect millions of people and can be an early indication of neurodegenerative diseases such as Parkinson’s disease, offering potential predictive value. “Sleep plays a central role in Parkinson’s disease, both as a biomarker for early signs of the disease and as a therapeutic target,” explains Prof. Joseph Claßen, second chairman of the German Society for Parkinson’s and Movement Disorders (DPG) e. V.

Sleep Disturbances in Parkinson’s Disease

Sleep disorders are a common complaint in medicine, and are particularly essential in Parkinson’s disease [1]. Disturbance of dream sleep, known as REM sleep behavior disorder (RBD), is one of the early signs of Parkinson’s disease, often occurring years before the first motor symptoms appear. However, deep sleep phases, which are not part of dream sleep, are also significantly disrupted in Parkinson’s disease [2]. These sleep disorders not only reduce quality of life due to a lack of rest but may also influence the course of Parkinson’s disease.

Sleep, Brain Cleansing, and Neurodegeneration

The glymphatic system, which removes waste products from brain metabolism, is increasingly a focus of Parkinson’s research. Like a “sewage treatment plant” for the brain, it flushes away pathogenic proteins that can clump together and damage nerve cells [3]. The glymphatic system is primarily active during sleep [4] and is critically dependent on brain regions that regulate sleep, such as the locus coeruleus, an area of nerve cells in the brainstem [5], [6]. Since Parkinson’s affects sleep-regulating centers early on, disrupting deep sleep, this could impair the removal of harmful substances and accelerate disease development. A recent study associated sleep apnea syndrome with the later development of Parkinson’s disease, independent of other factors, and found improvement with a sleep mask [7]. Improved sleep was also associated with a lower risk of illness [7]. “Sufficiently long sleep and solid sleep quality are becoming increasingly important as a promising therapy and biomarker approach in Parkinson’s research,” says Prof. Claßen. Advances in sensors and artificial intelligence methods allow for accurate, multimodal sleep measurement using polysomnography (PSG) and can even predict future disease risks, including Parkinson’s and dementia [8].

The Glymphatic System as a Therapeutic Target

Research is exploring how to directly improve the function of the glymphatic system. Pharmacological and other approaches are being investigated [9]. Animal experiments suggest that brain stimulation methods [10], [11] and improving cerebrospinal fluid drainage [12] can stabilize the glymphatic system.

Danish neurobiologist Prof. Maiken Nedergaard highlights the central importance of the glymphatic system for the development and potential treatment of Parkinson’s and related neurological disorders. “The exact mechanisms and therapeutic consequences are not yet understood. However, the results so far suggest that sleep could be an important key to influencing Parkinson’s disease,” concludes Prof. Claßen.