Associations between screen-time behaviours, physical activity, and positive and negative mental health among Irish adolescents

Emerging evidence suggests the association between screen-time and mental health is complex as findings thus far are mixed. This programme of research elucidated the individual and joint associations between screen-based behaviours, physical activity and negative (depressive and anxiety symptoms) and positive mental health among representative population samples of adolescents in Ireland. The systematic review established a dearth of evidence on the joint associations between screen-time, sedentary behaviour, and physical activity with positive and negative mental health. An initial exploratory, secondary analysis of data from 422 adolescents from the Children’s Sports Participation and Physical Activity Study (CSPPA) revealed positive associations between total screen-based sedentary behaviours and depressive symptoms (β=0.27, p=0.002). When screen-time type and mentally-active or mentally-passive context were examined in the same model, only mentally-active screen-time (e.g., computer use for fun) was positively associated with depressive symptoms (β=0.39, p=0.007).

Informed by initial findings, two novel cross-sectional studies of 1,756 adolescents’ expanded previous work by investigating associations between three types of screen-time (TV, computer, and phone use) and physical activity with depressive and anxiety symptoms. Results showed greater computer (depression: β=0.11, p=0.00, anxiety: β=0.09 p≤0.00) and phone use (depression: β=0.14, p=0.00, anxiety: β=0.08, p≤0.00) showed the strongest associations with depressive and anxiety symptoms. These studies also showed a moderating influence of physical activity level on the screen-time mental health relationship.

A final study among 879 adolescents advanced previous findings both replicating initial findings and expanding to quantify associations with positive mental health and potential dose-response relationships. Results replicated findings for depressive symptoms and the protective, moderating influence of physical activity. However, findings showed that TV viewing was inversely associated with anxiety symptoms (β=- 0.11 p≤0.00), and, conversely, higher phone use (β=0.11 p≤0.00) and physical activity (β=0.12 p≤0.00) were associated with better positive mental health. Dose-response relationships revealed a non-linear curve for depressive symptoms, indicating the optimal dose of TV watching may be between low and moderate hours of use (<5 hours), reinforcing that not all screen-time may be harmful.

Overall, the findings of this research programme demonstrate differential associations between screen-time, physical activity, and mental health outcomes. These associations differ based on type of screen-time mode, gender, level of physical activity, and mental health outcome. Additionally, not all screen-time appears to be detrimental, and moderation may be key for some screen-time modes. A protective, moderating influence of physical activity was observed for some types of screen-time behaviours. Regardless, this research highlights the need for further, rigorous investigations into the screen-time-physical activity and mental health relationship that focuses more on type of activity and considers that not all screen-time is detrimental.