Burdens of sedentary behaviour and symptoms of mental health disorders and their associations among 297,354 school-going adolescents from 68 countries

Background: Sedentary behaviour has become a critical public health issue among adolescents, with growing evidence linking it to adverse mental health outcomes. This study aimed to quantify the prevalence of sedentary behaviour and mental health symptoms among adolescents and explore their associations using data from countries across various WHO regions. Methods: We analysed data from the Global School-based Health Survey (GSHS) covering 68 countries between 2009 and 2018, including 297,354 adolescents aged 13-17 years. A meta-analysis with random effects was conducted to estimate the prevalence of sedentary behaviour (defined as spending 3 or more hours per day sedentary) and mental health symptoms (including loneliness, anxiety, suicidal ideation, suicide planning, and suicide attempts). Multi-level mixed-effect logistic regressions were used to investigate the associations between these factors. Results: Overall, 37.2% of adolescents engaged in sedentary behaviour, with a slightly higher prevalence among girls than boys (38.5% vs. 35.8%). The highest prevalence was in the Region of the Americas (46.9%), while the lowest was in the South-East Asia Region (25.7%), with significant variations between countries within each WHO region. Additionally, 19.0% of adolescents reported psychological distress, defined as experiencing at least two mental health symptoms. Sedentary behaviour was significantly associated with psychological distress (OR 1.34, 95% CI: 1.32-1.37) and each mental health symptom, with stronger associations observed among girls, younger adolescents, and those with lower parental support. A dose-response relationship was evident, with the odds of psychological distress increasing almost linearly with more hours spent sedentary (P for trend <0.001). Conclusions: This study highlights the high prevalence of sedentary behaviour and mental health symptoms among adolescents and demonstrates a clear dose-response association between sedentary behaviour and mental health outcomes. These findings underscore the urgent need for strategies aimed at reducing sedentary time among adolescents to promote better mental health.