In 106 emerging adults (median age 22) wearing actigraphy monitors, later sleep midpoint and bedtime independently predicted lower diet quality after adjusting for sex, BMI and race. Each step later was associated with lower DASH scores (0-9 scale; B ≥ -0.165, p ≤ 0.001) and lower Healthy Eating Index scores (0-100 scale; B ≥ -2.180, p ≤ 0.001). Participants with adequate sleep midpoint and more consistent wake times also ate better. Diet came from at least three days of food diaries; subjective sleep quality (PSQI) was assessed in 122 participants.
The pattern fits earlier work tying late chronotype and irregular sleep to more late-night eating, more sugary and ultra-processed food, and less produce. Sleep regularity has recently emerged as a strong predictor of mortality and cardiometabolic risk, sometimes outperforming duration, so its link to diet may be one pathway. Still, this cross-sectional design cannot show direction: poor diets may disrupt sleep, late schedules may drive poor food choices, or shift work and student schedules may drive both. A few days of self-reported diary data carries recall error, the sample is small and young, and the authors themselves flag likely bidirectionality. This is a preprint that has not been peer reviewed, so the estimates could shift. Practically, the findings add modest support for treating consistent, earlier sleep timing and diet as a package in young adults, but only trials can show whether fixing one improves the other. Confirmatory rather than paradigm-shifting.