Unraveling the Link between Sleep Disturbances and Parkinson's Disease: A Narrative Review.

Parkinson's disease (PD) is characterized by both motor and nonmotor symptoms, many of which originate from the pathophysiology of the disease and its progression. Nonmotor symptoms are diverse and can often be more debilitating for patients than motor symptoms. Among these, sleep disorders are particularly significant, as they can occur several years before the onset of motor symptoms and have profound implications for the patient's quality of life (QoL). Sleep problems typically manifest at all stages of the disease and are frequently regarded as a separate entity. This analysis aims to explore and summarize knowledge of the main sleep disorders associated with PD, their characteristics, prevalence, and treatment options. A comprehensive literature review was conducted, examining studies published on sleep disturbances in PD, focusing on the epidemiology, etiology, pathophysiology, implications, diagnosis, and treatment. Findings indicate that sleep disorders are prevalent in over 90% of patients with PD and often manifest years before the onset of motor symptoms. Specific disorders such as rapid eye movement sleep behavior disorder (RBD), insomnia, and excessive daytime sleepiness are highlighted as significant contributors to reduced QoL. The literature also emphasizes the complex interplay of factors, including dopaminergic treatments and disease progression, which exacerbate these disturbances. Sleep disorders are critical nonmotor symptoms of PD that significantly affect QoL. Early identification and tailored management of these symptoms are essential for improving patient outcomes. Further research is needed to develop effective treatment strategies that address the multifaceted nature of sleep disturbances in this population.