Abstract

Sleep disorders are highly prevalent in Parkinson’s disease (PD), affecting up to 90% of patients and significantly impairing quality of life. Emerging evidence suggested that sleep disturbances, particularly REM sleep behavior disorder (RBD), might reflect underlying neurodegenerative processes and predict disease progression. However, the precise impact of sleep disorders on non-motor symptoms (NMSs) in PD remains incompletely understood. This systematic review synthesized current evidence on the association between sleep disorders and NMS in PD, focusing on clinical correlates, pathophysiology, and therapeutic implications. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a comprehensive search of PubMed, Web of Science, SCOPUS, and Science Direct was conducted for studies examining sleep disorders and NMS in PD. Thirteen studies meeting the inclusion criteria were analyzed, including cross-sectional, longitudinal, and interventional designs. Risk of bias was assessed using the Newcastle-Ottawa Scale and Cochrane Risk of Bias Tool. RBD was consistently associated with worse motor and non-motor outcomes, including cognitive decline, autonomic dysfunction, and cortical atrophy. Insomnia and excessive daytime sleepiness correlated with increased neuropsychiatric symptoms and reduced quality of life. Mechanistic studies implicated dopaminergic and non-dopaminergic pathways, neuroinflammation, and circadian dysregulation. Interventions such as melatonin and Qigong improved sleep quality, while deep brain stimulation
modulated sleep architecture. Sleep disorders, particularly RBD, are significant predictors of NMS severity and disease progression in PD. Early identification and targeted interventions might improve clinical outcomes. Future research should integrate polysomnography, biomarkers, and standardized assessments to refine therapeutic strategies.

Key words: Parkinson’s disease, sleep disorders, REM sleep behavior disorder, non-motor symptoms, neurodegeneration, systematic review.