Associations Between Sleep Traits and Colorectal Cancer: A Mendelian Randomization Analysis

Background: The association between sleep and colorectal cancer (CRC) has been observed in many previous studies, however, evidence from randomized controlled trials (RCTs) is lacking. This study aimed to assess whether five major sleep characteristics are causally related to colorectal cancer risk through using Mendelian randomization(MR). Methods In this study, we performed the main MR analysis using inverse variance weighting (IVW), MR Egger, and weighted median. Independent genetic variants associated with five sleep-related traits (chronotype, sleep duration, insomnia, daytime napping, and daytime sleepiness) were selected as instrumental variables from the published Genome-Wide Association Study (GWAS) to assess the causal between sleep traits with CRC. We also performed sensitivity analyses to reduce bias and ensure the robustness of the results. Results MR analyses suggested that chronotype has an adverse effect on CRC risk(IVW, OR: 1.21, 95%CI: 1.01–1.44, P  = 0.029). While, there is no evidence to support a causal relationship between sleep duration, insomnia, daytime napping, and daytime sleepiness and CRC by the IVW method. Conclusions Our MR results indicate that chronotype promotes the occurrence of CRC. People should change their sleeping habits to decrease the risk of CRC.