Intervention to reduce recreational screen-time in adolescents: Outcomes and mediators from the 'Switch-Off 4 Healthy Minds' (S4HM) cluster randomized controlled trial

- Reductions in screen-time were not statistically significant.
- No intervention effects were found for mental health, physical activity or BMI.
- Intervention effect was partially mediated by increases in autonomous motivation.

IntroductionThe primary objective was to evaluate the impact of the 'Switch-off 4 Healthy Minds' (S4HM) intervention on recreational screen-time in adolescents.MethodsCluster randomized controlled trial with study measures at baseline and 6-months (post-intervention). Eligible participants reported exceeding recreational screen-time recommendations (i.e., > 2 h/day). In total, 322 adolescents (mean age = 14.4 ± 0.6 years) from eight secondary schools in New South Wales, Australia were recruited. The S4HM intervention was guided by Self-Determination Theory and included: an interactive seminar, eHealth messaging, a behavioral contract and parental newsletters. The primary outcome was recreational screen-time. Secondary outcomes included mental health (i.e., well-being, psychological distress, self-perceptions), objectively measured physical activity, and body mass index (BMI). Outcome analyses were conducted using linear mixed models and mediation was examined using a product-of-coefficients test.ResultsAt post-intervention, significant reductions in screen-time were observed in both groups, with a greater reduction observed in the intervention group (− 50 min/day versus − 29 min, p < 0.05 for both). However, the adjusted difference in change between groups was not statistically significant (mean = − 21.3 min/day, p = 0.255). There were no significant intervention effects for mental health outcomes, physical activity or BMI. Significant mediation effects for autonomous motivation were found.ConclusionsParticipants in both the S4HM intervention and control groups significantly reduced their screen-time, with no group-by-time effects. Enhancing autonomous motivation might be a useful intervention target for trials aimed at reducing adolescents' recreational screen-time.Trial registrationACTRN12614000163606.