Mettler · Journal of school psychology 2024 · randomized controlled trial · n=142

How we teach mindfulness matters: Adolescent development and the importance of informal mindfulness.

Level 2 - randomized trial

Individual randomized controlled trial with three parallel arms.

PubMed 38876551 · doi:10.1016/j.jsp.2024.101323 · record verified 2026-08-26

What was done

Adolescents (n = 142; 73.9% female) were randomly assigned to a 4-week formal mindfulness group (structured meditation), an informal mindfulness group (brief practices integrated into daily routine), or a comparison group. Mental health, well-being, and educational outcomes were evaluated across baseline to follow-up.

What was found

The informal mindfulness group showed a significantly higher intention to frequently use the strategies (p = .025, Cramer's V = .262) and increased dispositional mindfulness from baseline to follow-up (p = .049, partial eta squared = .034). This increase in dispositional mindfulness mediated significant indirect benefits on anxiety (indirect effect = -0.21, 95% CI [-0.36, -0.06]), depression (indirect effect = -0.15, 95% CI [-0.31, -0.03]), general stress (indirect effect = -0.16, 95% CI [-0.32, -0.04]), school-related stress (indirect effect = -0.15, 95% CI [-0.28, -0.05]), negative affect (indirect effect = -0.17, 95% CI [-0.35, -0.04]), and attentional control (indirect effect = 0.07, 95% CI [0.01, 0.13]). Direct effect sizes between groups on primary clinical outcomes were not reported in the abstract.

Why it matters

Standard meditation practices often face low adherence among teenagers. This trial demonstrates that brief, unstructured informal practices may be more developmentally acceptable and feasible for school-based implementation.

Limits

The sample was modest (n = 142), heavily female-skewed (73.9%), and relied on self-reported outcomes. The specific nature of the comparison group was not defined in the abstract, and long-term behavioral maintenance was not assessed.