Association between Time from Dinner to Bedtime and Sleep Quality Indices in the Young Japanese Population: A Cross-Sectional Study

Sleep quality (duration, efficiency, and latency) is directly associated with human health. An interventional study reported that the time of dinner influenced sleep latency, suggesting that it may also be associated with other sleep quality indices under free-living conditions. Therefore, we cross-sectionally examined the association between the time from dinner to bedtime (TDB) and sleep quality indices under free-living conditions in the young Japanese population. Based on the TDB, 264 participants were separated into three quantiles (T1, ≤3.79 h; T2, 3.80–4.94 h; T3, ≥4.95 h from dinner to bedtime). The T1 (mean ± standard error; 26.4 ± 2.2 min, p = 0.081) and T2 groups (30.8 ± 2.2 min, p = 0.001) showed longer sleep latency compared to the T3 group (19.6 ± 2.2 min), after adjusting for confounding factors. Sleep efficiency in the T1 group (77.5 ± 1.6%) tended to be greater than in the T3 group (72.1 ± 1.6%, p = 0.061), whereas sleep efficiency in the T2 group was not significantly different (77.0 ± 1.6%) from that in the T1 group. Therefore, shortened TDB was associated with prolonged sleep latency in free-living conditions. Meal timing, especially dinner, should be considered along with other sleep hygiene measures to improve human health.