The Healthy Learning Mind Project: Does a Universal Mindfulness Programme Reduce Stress Symptoms and Increase Self‐Kindness Among Adolescents in Schools?

ABSTRACT Chronic and increased levels of stress during adolescence are associated with academic performance, school dropout, and mental health challenges. This study investigated the effectiveness of the universal mindfulness‐based intervention (MBI) on adolescents' stress symptoms in schools through a cluster randomised controlled trial (cRCT) design. In addition, we examined the effectiveness of MBI on self‐kindness. Finally, we explored how age, gender, and an independent mindfulness practice moderated the effects on outcomes. A total of 3519 Finnish students aged 12–15 were randomised to a MBI group ( n = 1646), an active relaxation control group ( n = 1488), and an inactive control group that followed a routine school curriculum ( n = 385). Outcomes were measured at baseline (T0), 9 weeks post‐intervention (T9), and 26 weeks following the intervention (T26). Overall, those belonging to the MBI group reported a greater reduction in stress symptoms compared with the active control group at T9 and T26. Furthermore, students in the MBI group who carried out their mindfulness home practice regularly showed a greater decrease in stress symptoms compared with those who practiced less regularly. There were no MBI effects on self‐kindness. These results indicate that a universal MBI in schools may potentially support stress management among students.