Objective: We aimed to explore the association between bedtime at night and nonalcoholic fatty liver disease (NAFLD) measured by liver ultrasound transient elastography (LUTE). Methods: A total of 4572 individuals were included. The diagnosis of NAFLD was based on the controlled attenuated parameter (CAP) score of LUTE. CAP score similar to 263 dB/m and CAP score similar to 285 dB/m were used as the criterions for the diagnosis of NAFLD. Results: For the weekday bedtime, a positive association was identified in CAP (263 dB/m) (OR, 1.04 [95 %CI, 0.99, 1.09]) and CAP (285 dB/m) (OR, 1.00 [95 %CI, 0.95, 1.05]). For the weekend bedtime, a positive relationship was found in CAP (263 dB/m) (OR, 1.05 [95 %CI, 1.00, 1.10]). The positive relationship still presented in CAP (285 dB/m) (OR, 1.05[95 %CI, 1.00, 1.10]). When NAFLD defined as CAP score similar to 263 dB/m, the relationship between weekday bedtime and NAFLD was a straight line. For the weekend bedtime, the association was nonlinear. Before 22:00 o'clock, the association was positive (OR, 1.26 [95 %CI, 1.06, 1.50]), while between 22:00 and 1:00 o'clock, the relationship was negative (OR, 0.96 [95 %CI, 0.88, 1.05]) without a significant P value. After 1:00o'clock, the relationship was positive (OR, 1.26 [95 % CI, 1.02, 1.57]). Conclusion: Later bedtime was positive associated with NAFLD. (C) 2022 Elsevier B.V. All rights reserved.