A nationwide cluster-randomized trial in Danish elementary schools tested whether training teachers to deliver a ten-session mindfulness program improved student mental health. Among 1,728 students in grades 4–9, including 351 identified as at-risk, no statistically significant benefit was found on the primary outcome (Strengths and Difficulties Questionnaire Total Difficulties Score) at eight months; the effect size for at-risk students was negligible (Cohen's d = 0.05). Secondary analyses suggested the intervention may have increased perceived hyperactivity and inattention, especially among boys and younger students, and worsened self-rated health among at-risk students. The authors call for further research into mechanisms and implementation fidelity.
In a randomized controlled trial across 110 Danish schools, 191 teachers received Mindfulness-Based Stress Reduction (MBSR) or were placed on a wait-list. After 3 and 6 months, MBSR reduced perceived stress, anxiety, depression, and improved well-being. These improvements were partly explained by changes in self-reported resting state: less mind wandering (Discontinuity of Mind), more planning, and greater comfort. Changes in sleepiness also partially explained effects on stress and anxiety. No mediating effects were found for theory of mind, self-awareness, or somatic awareness. The findings suggest that altering resting state is one mechanism through which MBSR benefits mental health.