Non-linear relationships and interaction effects between different types of screen time and mental health issues among Hong Kong adolescents

Non-linear relationship of different types of screen time with adolescent mental health problems remains unclear. To identify non-linear relationships of internet gaming and social media use with probable depression and suicidal ideation and the thresholds in male and female adolescents. A school-based survey was conducted in 11,750 Hong Kong adolescents in 2020–2022. An anonymous questionnaire was used to assess screen time and mental health. Generalized additive models (GAM) and generalized linear mixed models (GLMM) were conducted to analyze gender-specific non-linear relationships, interaction effects, and dose-dependent relationships between screen time and mental health. Probable depression (64.3% vs. 52.0%) and suicidal ideation (35.0% vs. 24.6%) were more prevalent among girls. GAM revealed a U-shaped relationship between internet gaming time and probable depression (threshold: 1.5 h/day)/suicidal ideation (threshold: 2 h/day) in boys, but not in girls. GLMM showed that internet gaming within 1 h/day was associated with reduced suicidal ideation in boys (OR[95%CI] = 0.72[0.53, 0.99]) compared to non-users. For girls, social media use>1 h/day was associated with higher risks of probable depression (ORs range from 1.59 to 2.16, all p < 0.05) and suicidal ideation (ORs = 1.35 to 2.00, ps < 0.005) compared to non-users. However, boys’ social media use>2 h/day was associated with a higher risk of probable depression, but not for suicidal ideation. Positive interactions of internet gaming and social media use with mental health were found across genders (ps < 0.001). This study suggests a conservative cutoff of 1-h daily use for internet games and social media, respectively, for girls and boys. Regulating internet gaming and social media use concurrently may benefit adolescent mental health. • Internet gaming within 1 h/day was associated with reduced suicidal ideation compared to non-users in boys, but not in girls. • Girls' social media use>1 h/day significantly increased the risk of depression and suicidal ideation compared to non-users. • Boys' social media use>2 h/day increased depression, but not for suicidal ideation. • Positive interactions of Internet gaming and social media use with mental health were found across genders. • In general, 1-h daily use for internet games and social media, respectively, prevented the risk of mental health problems in both girls and boys.