Sleep and Sedentary Behavior Predict Severity in MASLD but Not MetALD/ALD: A Compositional Analysis

Daily movement behaviors are typically analyzed in isolation, ignoring their inherent competition for time within the 24-hour day. We examined whether the 24-hour composition of sleep, sedentary time, and physical activity was associated with liver stiffness in adults with steatotic liver disease (SLD) METHOD: This cross-sectional analysis used NHANES 2017-2018 data from 1,080 adults with SLD (889 MASLD, 101MetALD, and 90 ALD). Sleep, sedentary time, moderate-to-vigorous physical activity (MVPA), and other waking activity were modelled using isometric log-ratio coordinates in survey-weighted regression with log-transformed liver stiffness measurement (LSM). Isotemporal substitution analyses estimated LSM changes from reallocating 30 minutes between behaviors.

In MASLD, a greater sedentary time relative to active behaviors was associated with 5.79% higher LSM (95% CI 1.14-10.66%; p=0.027) after sociodemographic adjustment, attenuating after cardiometabolic adjustment (3.73%; p=0.086). Greater sleep relative to all other behaviors was independently associated with 15.55% lower LSM (95% CI -27.33% to -1.86%; p=0.044), persisting after full adjustment (-14.38%, 95% CI -25.58% to -1.49%; p=0.047). Replacing 30 minutes of sedentary time with sleep was associated with a larger LSM reduction (-1.69%, 95% CI -2.98% to -0.39%; p=0.011) than replacement with MVPA (-0.83%, 95% CI -1.32% to -0.33%; p=0.001). Among former drinkers, sedentary-to-sleep reallocation was associated with 2.24% lower LSM (95% CI -3.78% to -0.67%; p=0.005); among low drinkers, sedentary-to-MVPA reallocation was associated with 1.32% lower LSM (95% CI -2.19% to -0.44%; p=0.004). No substitution was significant in MetALD or ALD.

The 24-hour self-reported movement behavior composition is associated with liver stiffness in MASLD, with sedentary and sleep balance showing associations in opposite directions. This supports a personalized, whole-day approach to behavioral counseling in MASLD management.