Sleep Duration and Metabolic Syndrome: Mendelian Randomization Analyses in UK Biobank

Objectives: This Mendelian randomization (MR) study aimed to investigate the casual associations of genetically predicted sleep duration with metabolic syndrome (MetS) and its five individual components (e.g., central obesity, hypertension, low high-density lipoprotein cholesterol, hypertriglyceridemia, and hyperglycemia).MethodsIn 403,780 participants of White British ancestry from UK Biobank, this study conducted both linear and non-linear MR analyses to outline the shape of association of continuous sleep duration with MetS and its individual components. One-sample MR analyses was employed to determine causal association of genetically predicted short ( 8 h per day) sleep durations with MetS and each component. Results: Non-linear MR analyses revealed a L-shape association between genetically predicted sleep duration and MetS, as well as its components except for hypertension. One sample MR analyses demonstrated adverse effects of genetically predicted short sleep duration on risk of metabolic outcomes, including MetS (OR = 1.13, 95% confidence interval (CI) = 1.03 to 1.25) and two individual components (e.g., central obesity (OR = 1.19, 95% CI = 1.05 to 1.33) and hypertriglyceridemia (OR = 1.08, 95% CI = 1.01 to 1.16). However, causal relationships of genetically predicted long sleep duration with MetS or its individual components were not found (all p > 0.05). Conclusions: The present MR study indicated that short sleep duration but not long sleep duration was a potentially causal risk factor for MetS. Future studies applying sleep extension to prevent MetS among those with insufficient sleep duration are indicated. Funding Statement: Prof. Qingshan Geng and Dr. Huan Ma were supported by the grant of the High-level Hospital Construction Project of Guangdong Provincial People’s Hospital (DFJH201811D Dr. Shizhi Ai was supported by the National Natural Science Foundation of China (81801315) and the “Impact Postdoctoral Fellowship Scheme of The Chinese University of Hong Kong”. The sponsors or funders did not play any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. Declaration of Interests: All authors report no conflict of interest.