Effects of later dinner timing on subsequent metabolic function and nocturnal sleep in healthy young women.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 41975458 · doi:10.1186/s40101-026-00430-0
What was done
A randomized crossover trial in 13 healthy young women (mean age 21.4 ± 0.6 years) evaluated two dinner timings: 1 hour versus 5 hours before habitual bedtime. Each condition lasted 6 days (Day 0 baseline, Days 1–4 intervention, Day 5 post-intervention). Test dinners provided 709–740 kcal with fixed macronutrient composition. Sleep was assessed via overnight electroencephalography (EEG) on Day 0 and Day 4, interstitial glucose was monitored continuously via continuous glucose monitoring (CGM), and a morning oral glucose tolerance test (OGTT) was conducted on Day 5.
What was found
On Day 4, eating dinner 1 hour before bedtime led to significantly shorter total sleep time (p = 0.013), reduced sleep efficiency (p = 0.040), increased wake after sleep onset (WASO, p = 0.017), a higher Arousal Index (p = 0.041), more stage-shifts (p = 0.016), and a higher Stage-Shift Index (p = 0.003) compared to dinner 5 hours before bedtime. Postprandial glucose incremental area under the curve (iAUC) showed a significant interaction effect (p = 0.042), with lower values on Days 3 and 4 than Day 1 (p = 0.090). Next-morning OGTT outcomes showed no significant differences between conditions. Absolute values and effect sizes for sleep parameters were not reported in the abstract.
Why it matters
This study provides objective polysomnographic evidence that eating dinner immediately before bedtime compromises sleep continuity and architecture in healthy individuals, even when meal composition and calorie content are held constant.
Limits
The sample size was very small (n = 13) and limited strictly to young, healthy women, precluding generalization to men, older populations, or individuals with metabolic or sleep disorders. The intervention duration was short (4 days per condition), and exact numerical means and confidence intervals were omitted from the abstract.
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