Working hours and nonalcoholic fatty liver disease according to sleep duration.

There is no study on the relationship between working hours and nonalcoholic fatty liver disease (NAFLD). The objective of the present study was to determine the relationship between working hours and NAFLD by sleep duration using a large set of abdominal ultrasonography examination data. Data from 194,625 patients who underwent health examinations from 2015 to 2017 were analyzed. Chi-square tests, linear-by-linear association and ANOVA were performed to compare general characteristics according to working hours. Multivariate logistic regression analysis was performed to determine the relationship between working hours and NAFLD by sleep duration. There was no significant relationship between working hours and NAFLD prevalence in the group of short sleep duration of ≤5 hours or the group of long sleep duration of ≥7 hours. The risk of NAFLD in the >52 working hour group was significantly higher (aOR, 1.09; 95% CI, 1.04-1.14) than that in the 40- to 52-hour working hour group after adjusting for confounding factors in the 5- to 6-hour sleep duration group. There was no significant difference between ≤40 working hours and 40 ~ 52 working hours in the 5 ~ 6 hours sleep duration group (aOR, 1.02; 95% CI, 0.97-1.06). In general, working hours were significantly related to NAFLD. There was a difference in the relationship between working hours and NAFLD according to sleep duration.