To investigate the association between circadian syndrome (CircS) and metabolic dysfunction-associated steatotic liver disease (MASLD).

Utilizing data from the 2017—2020 US National Health and Nutrition Examination Survey (NHANES), 2 060 adults aged ≥20 years were included. MASLD was diagnosed based on vibration-controlled transient elastography (CAP ≥274 dB/m) and metabolic risk criteria. CircS was defined as meeting ≥4 components (abdominal obesity,dyslipidemia, hypertension, hyperglycemia, sleep duration ≤6 h/day, depressive symptoms). Multivariable logistic regression was used to analyze the association between CircS, the number of CircS components, and MASLD [odds ratio (OR) and 95%confidence interval(CI)], adjusting for demographic and lifestyle confounders. Subgroup analyses were performed, and a MASLD risk prediction nomogram was constructed using LASSO-selected variables.

Among the participants, 786 (38.2%) had MASLD and 839 (40.7%) had CircS. The fully adjusted model revealed a significant positive association between CircS and MASLD (OR=3.95, 95% CI: 3.19-4.90). The number of CircS components showed a dose-response relationship with the presence of MASLD (P for trend <0.05), with individuals having ≥6 components exhibiting the highest odds of MASLD (OR=8.35, 95% CI: 5.27-13.50). Subgroup analysis indicated a stronger association in younger adults aged <50 years (OR=5.69,95% CI: 4.12-7.87). The nomogram incorporating CircS demonstrated moderate predictive ability (training set AUC=0.715).

This study is the first to reveal an independent positive association between CircS and MASLD, particularly pronounced in younger adults, with a dose-response relationship. CircS may serve as a potential association marker for MASLD,suggesting that interventions targeting circadian rhythm disruption could represent a novel prevention and management strategy.