Socioeconomic inequalities in health behaviours pre- and post-COVID-19 among Japanese adolescents: a three-wave repeated cross-sectional survey

Background: Changes in socioeconomic inequalities in health behaviours following the COVID-19 pandemic remain known. In this study, we examined changes in socioeconomic inequalities in adolescent 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, and analysed 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 assessed using the slope and relative indices of inequality across equivalent household income levels. Results: Significant quadratic trends showed narrowing inequalities in breakfast consumption by 2021 and renewed inequalities in 2023. Socioeconomic inequalities in breakfast consumption resurged by 2023, with lower prevalence in lower income groups. No inequalities and trends in inequalities were observed in sleep duration or bowel movements. PA declined for lower-income groups, while ST worsened over time. Discussion: Socioeconomic disparities in breakfast consumption resurged among Japanese adolescents post-COVID-19, with declines in the lower income groups and improvements in the higher income groups. The overall adherence to PA and ST guidelines showed worsening trends, and socioeconomic inequalities in PA showed minimal variation. Sustained public health initiatives are essential to address these disparities.