Background The relationship between sleep patterns and nonalcoholic fatty liver disease (NAFLD) is inconclusive, and their interaction with genetic susceptibility remains poorly understood. This study used data from the UK Biobank to investigate these associations.

Methods This prospective cohort comprised 446,979 participants from the UK Biobank and was followed until 2022. Exposure consisted of four daily sleep patterns: sleep duration, napping, snoring, and difficulty getting up. The genetic risk score for NAFLD was calculated. The outcome was severe NAFLD (defined as hospital admission or death). Cox proportional hazard regression was used to determine multivariable hazard ratios (HRs) and 95% confidence intervals (95% CIs).

Results During a median follow-up of 13.64 years, 4,673 severe NAFLD cases were recorded. U-shaped associations between sleep duration and severe NAFLD incidence were observed. In comparison to 7–8 hours of sleep, sleeping 10 hours had an HR of 1.68 (95% CI: 1.22-2.32). Additionally, daytime napping (HR = 1.29 [1.13–1.46]) and snoring (HR = 1.16 [1.08–1.24]) were linked to a higher risk of severe NAFLD. Easy to get up had a decreased risk (HR = 0.74; 95% CI: 0.63-0.85). Lastly, individuals with abnormal sleep patterns and high genetic risk exhibited the highest risk of severe NAFLD, whereas those with appropriate sleep patterns and high genetic risk had reduced risks.

Conclusions Inappropriate sleep patterns—sleeping more or less than 7–8 hours/day, napping, simple snoring, and getting up difficulty—were independently associated with severe NAFLD. Moreover, these poor sleep patterns seemed to amplify the impact of high genetic risk.