Association of sleep duration and sleep quality with non-alcoholic fatty liver disease

Objective To investigate the association of sleep duration and sleep quality with NAFLD among subway workers, and to explore the potential mediation effect of body mass index (BMI) on the association between sleep duration and NAFLD.Methods The study was a cross-sectional study, which 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). Based on sleep duration, the participants were divided into 5 groups: <6 h, 6-＜7 h, 7-＜8 h, 8-＜9 h, and ≥9 h. According to the PSQI score, the subjects were categorized into 3 groups: good (0-5 points), fair (6-10 points), and poor (11-21 points) sleep quality. Logistic regression model was used to investigate the association of sleep duration and sleep quality with NAFLD. Mediation analysis was employed to further evaluate the potential mediation effect of BMI on the association between sleep duration and NAFLD.Results Among the 8393 participants, 2472 were NAFLD patients. Compared with participants with a sleep duration of 7-<8 h, the multivariable-adjusted OR (95% CI) for those who slept ≥9 h was 0.79 (0.67-0.93). For each 1-hour increase in sleep duration, the OR (95% CI) was 0.91 (0.87-0.95) for NAFLD. Mediation analysis indicated that BMI mediates 87.03% of the association between sleep duration and NAFLD. Compared with subjects with good sleep quality, the multivariable-adjusted OR (95% CI) for those with fair and bad sleep quality was 1.08 (0.92-1.26) and 1.20 (0.93-1.55), respectively. For each point increase in the PSQI score, the OR (95% CI) was 1.02 (1.00-1.05) for NAFLD.Conclusion A sleep duration of ≥9 h was associated with a lower risk of NAFLD. BMI partially mediated the association between sleep duration and NAFLD.