BACKGROUND: Changes in socioeconomic inequalities in health behaviours following the COVID-19 pandemic remain unknown, particularly among Japanese school-aged adolescents. Therefore, in this study, we examined changes in socioeconomic inequalities in school-aged adolescents' health behaviours, including physical activity (PA), screen time (ST), sleep duration, breakfast consumption, and bowel movement frequency, before and after the pandemic. METHODS: This three-wave repeated cross-sectional study utilised data from the 2019, 2021, and 2023 National Sports-Life Survey of Children and Young People in Japan, analysing data from 766, 725, and 604 participants aged 12-18 years, respectively. Favourable health behaviours were defined as moderate-to-vigorous PA of ≥60 min/day, ST <2 h/day, sleep duration of 8-10 h, daily breakfast consumption, and bowel movements at least every 3 days. Absolute and relative socioeconomic inequalities were quantified using the slope index of inequality (SII) and the relative index of inequality (RII). Temporal changes were analysed using quadratic trend analyses, employing interaction terms between socioeconomic status and survey year. RESULTS: Significant quadratic trends indicated that socioeconomic inequalities in breakfast consumption decreased substantially from 2019 (SII: 20.7%, RII: 5.09) to 2021 (SII: -0.1%, RII: 0.95) but resurged in 2023 (SII: 16.2%, RII: 3.70). This resurgence may have been primarily driven by changes among those in the moderately low-income (poverty level II) and higher-income groups, which had a breakfast consumption rate of 81.0, 87.0, and 76.4% in 2019, 2021, and 2023, and 88.7, 82.1, and 87.5%, respectively. Among low-income households, adherence to PA recommendations significantly declined from 18.6% to 5.3%, and ST adherence worsened over the study period. No significant inequalities or trends were observed for sleep duration or bowel movement frequency across survey years. CONCLUSIONS Socioeconomic disparities in breakfast consumption among Japanese school-aged adolescents resurfaced after initially narrowing during the pandemic, likely driven by changes in moderately low-income and higher-income groups. Among low-income households, adherence to PA and ST guidelines declined over time. However, at the population level, socioeconomic inequalities in PA did not exhibit a consistent trend of widening or narrowing. This study highlights the need for sustained public health initiatives to address these socioeconomic disparities.
Adolescent ; Child ; Female ; Humans ; Male ; Breakfast ; COVID-19/psychology* ; Cross-Sectional Studies ; Exercise ; Health Behavior ; Japan/epidemiology* ; Screen Time ; Sleep ; Socioeconomic Factors ; East Asian People

BACKGROUND: Smoking among Japanese adolescents has decreased noticeably. However, little is known whether the decreasing trend in adolescent smoking can be seen across all socioeconomic status (SES) groups. This study aimed to examine trends in socioeconomic inequalities in smoking among Japanese adolescents between 2008 and 2016. METHODS: We conducted a repeated cross-sectional study using data from three surveys of high school students in Okinawa, Japan, in 2008, 2012, and 2016. The study participants consisted of 7902 students in grades 10 through 12 (15-18 years). Smoking was assessed as current cigarette use. SES indicators included familial SES (parental education and family structure) and student's own SES (school type). To evaluate absolute and relative inequalities, prevalence differences (PDs) and ratios (PRs) between low and high SES groups were estimated. The slope index of inequality (SII) and relative index of inequality (RII) were also calculated. RESULTS: Smoking prevalence among boys and girls significantly declined from 11.5% and 6.2% in 2008 to 4.7% and 1.9% in 2016, respectively. Similar decreasing trends in smoking were found among most of the SES groups. The PDs and SII for parental education in boys and family structure in girls decreased over time while those for school type persisted among boys and girls. The PRs and RII for school type in boys increased while those for other SES indicators among both sexes remained stable over time. CONCLUSIONS Smoking among Japanese adolescents has been declining and time trends of socioeconomic inequalities in smoking varied by absolute and relative measures. Further policies and/or interventions to reduce smoking inequalities should focus on the context of schools, especially in vocational high schools.
Adolescent ; Cross-Sectional Studies ; Female ; Humans ; Japan ; Male ; Prevalence ; Socioeconomic Factors ; Tobacco Smoking/epidemiology*

This study examined the relationship between meeting the World Health Organization’s (WHO) 24-Hour Movement Guidelines for the Early Years and motor skills and cognitive function in preschool children. Participants were 4-year-old boys and girls in urban and rural areas (n=69). Physical activity was measured using a triaxial accelerometer (ActiGraph GT3X). Screen time and sleep duration were assessed via self-report by guardians. Meeting the 24-h movement guidelines was defined as: 10 to 13 h/night and nap of sleep, ≤1 h/day of sedentary screen time, and at least 180 min/day more than 1.5 METs. Motor skills were evaluated by the Ages & Stages Questionnaires, Third Edition (ASQ-3). Executive functions (shifting, visual-spatial working memory and inhibition) were evaluated by the Early Years Toolbox (Japanese translation). The prevalence of children meeting all three recommendations was 7.2% and 7.2% met none of the three recommendations. Children meeting physical activity recommendation had a better inhibition score compared to children meeting none of the recommendation (p=0.005). While, children not meeting the sleep recommendation had a better inhibition score compared to children meeting of the recommendation (p=0.042). In conclusion, meeting the physical activity or sleep recommendations were positively or negatively associated with the inhibition score. On the other hand, meeting none of the sedentary behaviour and the 3 recommendations was not associated with motor skills or cognitive function.

In order to obtain the basic data for the relationship between factors related to sports and bone density of high school girls, bone densities of a heel were measured, and physical characteristics and living backgrounds on exercises were surveyed. The subjects were one-hundred and forty two girls (15-18 years, mean±SD=16.5±0.84 years) of a high school in Nagano prefecture, accepted our visiting bone health check. Bone density was measured by ultrasound bone-densitometer ‘Achilles’ (Lunar) . As for the data, we obtained the stiffness index (Stiffness) with a self-registered questionnaire for the items of physical and exercise factors for the girls in puberty. High school girls who belong to a sport club have significantly higher bone density than other girls. In detail, those who do the sports which consist of mainly running or jumpping, have significantly higher bone density than others who do no sports. There also were significants on the kinds of sports, on the frequency of sports and on the duration of sports. Moreover, those who had the regular sports history have higher bone density than those who had no regular sports history, and the mean Stiffness of the group that care to do physical exercises daily was higher than those who do not care to do exercises. These results suggest that there are many kinds of factors related to sports which favourably contribute to obtain sufficient bone mass of high school girls who are in a developmental stage.