Does physical activity moderate the association between screen time and psychosocial development in early childhood? Analysis of a longitudinal infant cohort study in Ireland.

The objective of this study was to explore the extent to which the association between screen time and psychosocial development in preschool children differed between the sexes and according to their frequency of engagement in physical activity. Data are based on a prospective cohort of Irish children, collected between 2010 and 2013 when children were ages 3 (n=9786) and 5 years (n=9001). Children's screen time (h/day), psychosocial development (Strengths and Difficulties Questionnaire), and physical activity (bouts/week) were assessed via caregiver report. The magnitude of the association between screen time and changes in behavioural difficulties differed significantly between the sexes. For boys, the association between increased screen time and the onset of behavioural problems coincided directly with a reduction in their frequency of engagement in physical activity. The association between screen time and changes in behavioural difficulties was not moderated by girls' engagement in physical activity, however; and there was no difference in the association between screen time and prosocial behaviours at different frequencies of engagement in physical activity for either boys or girls.Conclusions: Results support recommendations to establish greater balance between physical activity and sedentary behaviours in token economy systems to minimise the negative effects of excessive screen time. What is Known: • Provision of screen time has become normalised as a behavioural reinforcer for use with young children. • Screen viewing above recommended guidelines is associated with behavioural problems that reflect poor self-regulation. What is New: • Boys' levels of engagement in physical activity moderated the relationship between screen time and changes in behavioural difficulties between the ages of 3 and 5 years. • Neither screen time nor physical activity was significantly associated with changes in prosocial behaviours between the ages of 3 and 5 years for either boys or girls.