Sleep disorders and an increased risk of Parkinson's disease in individuals with non-apnea sleep disorders: a population-based cohort study.

Sleep disorders are common non-motor symptoms in patients with Parkinson's disease. Our study aims to explore the relationship between non-apnea sleep disorders and future Parkinson's disease. This is a cohort study using a nationwide database. The participants were recruited from the Taiwan National Health Insurance Research Database between 2000 and 2003. A total of 91 273 adult patients who had non-apnea sleep disorders without pre-existing Parkinson's disease were enrolled. An age-, gender-, income-, urbanization- and Charlson comorbidity index score-matched control cohort consisting of 91 273 participants was selected for comparison. The two cohorts were followed for the occurrence of Parkinson's disease, death or until the end of 2010, whichever came first. The Kaplan-Meier analyses revealed patients with non-apnea sleep disorders tended to develop Parkinson's disease (log-rank test, P < 0.001). After a multivariate adjustment in a Cox regression model, non-apnea sleep disorders was an independent risk factor for the development of Parkinson's disease [crude hazard ratio: 1.63, 95% confidence interval (CI): 1.54-1.73, P < 0.001; adjusted hazard ratio: 1.18, 95% CI: 1.11-1.26, P < 0.001]. In the subgroup analysis, patients with chronic insomnia (lasting more than 3 months) had the greatest risk (crude hazard ratio: 2.91, 95% CI: 2.59-3.26, P < 0.001; adjusted hazard ratio: 1.37, 95% CI: 1.21-1.55, P < 0.001). In conclusion, this study revealed that non-apnea sleep disorders, especially chronic insomnia, are associated with a higher risk for future Parkinson's disease.