Human study · Research · 5 Nov 2026
In 4,483 Korean adults ages 40 and older, a 2-hour social jetlag lined up with higher body fat on a DXA scan
Source: PLOS One
What the research found
PLOS One published a cross-sectional study on 5 November 2026. Kim and Bae used the 2024 Korea National Health and Nutrition Examination Survey. Social jetlag is the gap between the midpoint of sleep on weekdays and weekends. Among 4,483 adults ages 40 and older who reported both schedules, 267 people (6.0 percent) had a gap of at least 2 hours. In models adjusted for age, sex, height, average sleep duration, income, education, smoking, alcohol, activity, hypertension, and diabetes, that group had higher dual-energy X-ray absorptiometry body fat: total fat +0.81 percentage points (p = 0.025), subtotal fat +0.86 (p = 0.025), and trunk fat +1.01 (p = 0.036). Body mass index and waist circumference were not higher. The fat differences remained after an adjustment for depressive symptoms. They weakened and were no longer significant after a chronotype proxy, and they did not hold when jetlag was corrected for sleep debt. Sleep-duration swings showed no link. The authors call the result hypothesis-generating and say ordinary social jetlag may partly be weekend catch-up sleep. Not a trial. DOI 10.1371/journal.pone.0362068. Not medical advice.
Evidence level: Human study. A study in people, but an association isn't proof of cause.
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