In 1,080 US adults with steatotic liver disease (NHANES 2017-2018), compositional analysis of sleep, sedentary time and moderate-to-vigorous activity showed that in MASLD (n=889), proportionally more sleep was associated with 14.4% lower liver stiffness after full adjustment. Greater sedentary time tracked with higher stiffness, though this faded after cardiometabolic adjustment. Swapping 30 minutes of sitting for sleep predicted a 1.69% reduction, roughly double the 0.83% for the same swap into vigorous activity. No substitution reached significance in MetALD or ALD.
The standout result is sleep outperforming exercise per minute, which cuts against the usual 'move more' counseling. Treat it cautiously. This is a cross-sectional analysis with self-reported behavior, so reverse causation is plausible: advanced fibrosis and its symptoms may themselves disrupt sleep or reduce activity. Single-day-type NHANES data cannot capture habitual patterns, and the non-MASLD groups (101 and 90 people) were too small to conclude that these behaviors don't matter there. Subgroup findings among former and low drinkers rest on even thinner data and multiple comparisons. The effect sizes per 30-minute swap are small, though the whole-composition estimates are larger. The compositional framework is the real contribution, since it accounts for the fact that an extra hour of anything displaces something else. Practically, it nudges MASLD patients and clinicians to treat sleep as a modifiable target alongside exercise and diet, but this is hypothesis-generating work that needs longitudinal and interventional confirmation.