Abstract
OBJECTIVES: We investigated the association between children's waking time and bedtime and contents of home meals, focusing on 'skipping breakfast' and 'meal of staple food, main dish, and side dish' (SMS meal). METHODS: A cross-sectional survey concerning children's lifestyle habits and dietary habits was conducted at seven primary schools within Saga Prefecture in northern Kyushu, Japan, with 2457 parents/guardians participating. Logistic regression analyses were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association of sleep hours, wake-up time, and bedtime, with breakfast skipping and having SMS meals. RESULTS: Elementary schoolchildren sleeping for ≥9 hours were more likely to have parents/guardians in their 30s, who were full-time parents and maintained a healthy diet. Wake-up times and bedtimes were significantly associated with breakfast skipping frequency. Compared to the wake-up time from 6:30 to 6:59, ORs for the frequency of skipping breakfast was 0.52 (95% CI: 0.36-0.74, p < 0.001), for those waking before 6:29 and 2.23 (95% CI: 1.64-3.04; p < 0.001) for those waking after 7:00.Frequency of skipping breakfast decreased with earlier bedtimes. Compared to bedtimes from 21:00 to 21:59, ORs for having SMS meals were 0.64 for those with bedtimes before 21:00 (95% CI: 0.25-1.64) and 2.35 for those with bedtimes after 22:00 (95% CI: 1.77-3.11, p < 0.001). Compared to wake-up times from 6:30 to 6:59, waking up both before 6:29 (OR = 0.77, 95% CI: 0.63-0.94, p < 0.01) and at 7:00 or after (OR = 1.30, 95% CI: 1.00-1.69, p = 0.05) were associated with breakfast and dinner with SMS meals. A statistical interaction existed between wake-up time/bedtime and breakfast skipping. Compared to those waking before 6:30 and sleeping before 22:00, waking after 7:00 and sleeping after 22:00 was associated with skipping breakfast (OR = 2.11, 95% CI: 1.48-3.01; p for interaction = 0.04). Thus, children should sleep before 22:00 and wake up before 7:00 to prevent breakfast skipping and ensure a well-balanced diet with SMS meals. The 'Early to Bed, Early to Rise, and Don't Forget Your Breakfast' initiative significantly improved elementary schoolchildren's eating habits. CONCLUSIONS: Sleep hours, bedtime, and wake-up times are important factors affecting Japanese schoolchildren's dietary habits, specifically in terms of breakfast skipping and having SMS meals.