Exploring the causal association between 6 sleep traits and Parkinson disease

Parkinson disease (PD) is a prevalent neurodegenerative condition that significantly impacts the quality of life of patients. The investigation of the causal relationship between sleep characteristics and PD is of great significance for the development of effective strategies for early prevention and intervention. This research employed bidirectional 2-sample Mendelian randomization (MR) using genome wide association studies data to investigate the causal association between chronotype, daytime dozing, sleep duration, insomnia, nap during day, snoring, and PD. Inverse variance weighted (IVW) was used as the primary method. The Cochran Q test was used to check the heterogeneity of the single nucleotide polymorphisms effect. The MR Egger intercept test assessed horizontal pleiotropy. Lastly, leave-one-out analysis ensured result stability. The results of the forward MR indicated that the IVW method revealed significant positive correlations between chronotype (odds ratio [OR] = 1.240, 95% confidence interval [CI] = 0.770-1.998, P = .377), daytime dozing (OR = 2.566, 95% CI = 0.351-8.771, P = .353), sleep duration (OR = 2.069, 95% CI = 1.247-3.433, P = .005) with PD. However, insomnia (OR = 0.823, 95% CI = 0.206-3.290, P = .738), nap during day (OR = 0.831, 95% CI = 0.198-3.494, P = .801), and snoring (OR = 0.262, 95% CI = 0.050-1.380, P = .114) exhibited negative correlations with PD. In the reverse MR, the IVW results suggested that there were no causal associations were found between PD and chronotype (OR: 1.000, 95% CI: 0.965-1.036, standard error [SE] = 0.018, P = .998), daytime dozing (OR: 0.990, 95% CI: 0.979-1.002, SE = 0.006, P = .101), sleep duration (OR: 1.007, 95% CI: 0.992-1.023, SE = 0.008, P = .353), insomnia (OR: 0.993, 95% CI: 0.976-1.010, SE = 0.009, P = .397), nap during day (OR: 1.014, 95% CI: 1.000-1.028, SE = 0.007, P = .057), and snoring (OR: 0.996, 95% CI: 0.986-1.005, SE = 0.005, P = .384). The findings were generally robust in the sensitive analysis. Chronotye, daytime dozing, and sleep duration may be risk factors for PD. However, the causal relationship between these sleep characteristics and PD still needs to be verified by larger, more detailed phenotypic studies.