Intersection of Sleep Disorders and Parkinson Disease: Unveiling the Bidirectional Relationship.

Background: Patients with Parkinson's Disease (PD) frequently exhibit non-motor symptoms, particularly sleep disturbances. Sleep disorders in PD patients are intricately linked to the pathogenesis and progression of PD itself, exacerbating neurodegenerative processes and worsening patient quality of life.

Objectives: This review underscores the significance of sleep disorders in PD, highlighting their prevalence, impact on disease progression, and the bidirectional relationship between sleep disruption and neurodegeneration. It aims to enhance clinician awareness for better diagnosis and management of sleep-related comorbidities in PD.

Methods: A comprehensive literature search was conducted in PubMed and Scopus using key terms such as "sleep disorders", "Parkinson's disease", "REM sleep behavior disorder", "restless legs syndrome", "insomnia", "obstructive sleep apnea", "excessive daytime sleepiness", "circadian rhythm disorders", "sleep and neurodegeneration".

Results: Sleep disorders are prevalent in PD affecting up to 90% of patients. Conditions such as insomnia, REM sleep behavior disorder, restless legs syndrome, obstructive sleep apnea, excessive daytime sleepiness, and circadian rhythm disorders are commonly reported. These disorders are linked to multifactorial biological mechanisms and are associated with more severe disease phenotypes. Of note, several evidence shows that sleep abnormalities may contribute to neuroinflammation and neurodegeneration, further accelerating the disease course.

Conclusions: Sleep disturbances are critical non-motor symptoms in PD. Early diagnosis and tailored management of sleep disorders are essential for improving clinical outcomes and potentially offering neuroprotective benefits.