Differential effects of sleep duration on cardiovascular risk in metabolic-associated fatty liver disease vs. without metabolic-associated fatty liver disease: evidence from National Health and Nutrition Examination Survey and Mendelian randomization

Background Cardiovascular disease (CVD) risk increases in patients with metabolic-associated fatty liver disease (MAFLD). While sleep duration is linked to CVD risk, it is unclear whether it differs between individuals with and without MAFLD. Methods Data from the National Health and Nutrition Examination Survey (2007–2020; n = 10 386) were analyzed using multivariable logistic regression to examine the relationship between sleep duration and CVD. Subgroup analyses and a restricted cubic spline model assessed interactions and potential nonlinear associations, while Mendelian randomization (MR) was used to infer causality. Results Long sleep duration (≥9 h) was associated with an increased CVD risk in MAFLD patients [ P = 0.005, odds ratio (OR) = 1.92, 95% confidence intervals (CI): 1.22–3.02], while short sleep duration (≤6 h) was linked to a higher CVD risk in non-MAFLD individuals ( P = 0.030, OR = 1.63, 95% CI: 1.05–2.52). Subgroup analysis revealed that marital status modified this association in MAFLD patients. A U -shaped relationship was observed, with the lowest CVD risk occurring at 6.7 h of sleep for MAFLD patients and 7.9 h for non-MAFLD individuals. MR suggested a causal link ( P = 0.03, OR = 1.42, 95% CI: 1.02–1.97), with the results remaining robust after adjusting for potential confounders. Conclusion Long sleep duration increases CVD risk in MAFLD patients, with a U -shaped relationship indicating the lowest risk at 6.7 h of sleep in MAFLD and 7.9 h in non-MAFLD individuals. MR analysis suggests a causal link between sleep duration and CVD.