Objective  To investigate the association of sleep duration and sleep quality with metabolic associated fatty liver disease (MAFLD) among subway workers.

Methods  The study was a cross-sectional study, which was conducted based on workers from the Wuhan Metro Group Co., Ltd.. Sleep duration and sleep quality were obtained by the Pittsburgh Sleep Quality Index (PSQI). Logistic regression model was used to investigate the association of sleep duration and sleep quality with MAFLD. Mediation analysis was employed to evaluate the potential mediation effect of BMI on the association between sleep duration and MAFLD.

Results  A total of 8,650 subjects were enrolled, including 2,420 cases in the MAFLD group and 6,230 cases in the non-MAFLD group, resulting in MAFLD prevalence rate of 27.98%. Compared with participants with a sleep duration of 7~<8 h, those slept for 6~<7 h had a 19% increased risk of MAFLD [OR=1.19, 95%CI (1.02, 1.04)], and those slept for ≥9 h had a 19% decreased risk of MAFLD [OR=0.81, 95%CI (0.69, 0.95)] after adjusted for multiple covariates. For each 1-hour increase in sleep duration, the risk of MAFLD decreased by 8% [OR=0.92, 95% CI (0.88, 0.96)]. No significant association was observed between sleep quality and MAFLD. Restricted cubic spline analyses did not find a significant nonlinear association of sleep duration and sleep quality with MAFLD. Subgroup analyses showed that the association between sleep duration and MAFLD was more pronounced among non-current drinkers, a significant interaction was found between sleep duration and drinking status (Pinteraction=0.009). Mediation analysis indicated that the average causal mediation effect of BMI in the association between sleep duration and MAFLD was -0.04, with a mediation proportion of 93.8%.

Conclusion  Among subway employees, compared to those who sleep 7~<8 h, a sleep duration of 6~<7 h was associated with a higher risk of MAFLD prevalence, while ≥9 h was associated with a lower risk. BMI mediated the association between sleep duration and MAFLD. There was no significant association between sleep quality and MAFLD.

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