Background There is a call for sustainable, evidence-based interventions in schools to promote mental health in schoolchildren. Our primary aim of this trial is to evaluate the effectiveness in vulnerable pupils of a school teacher training programme to teach mindfulness (“.b” programme) as a part of compulsory class room teaching in Danish schools on the pupils’ self-reported mental health at 6-month follow-up. Our secondary aim is to evaluate the effectiveness of the school teacher training programme to teach the “.b”-programme as a part of compulsory class room teaching among the total pupil population on the pupils’ self-reported mental health at 3 and 6 months after baseline. Methods The pragmatic cluster two-armed randomised controlled trial includes 110 municipal or private schools from all five regions in Denmark; 191 school teachers and approximately 2000 pupils at 11–15 years of age. Exclusion criteria; for schools: < 100 pupils; for pupils: parental opt out. Our intervention consists of (A) a school teacher training programme and (B) the “.b”-programme delivered as part of compulsory class room teaching in schools to pupils at the age of 11–15 years. The pupils in the control schools receive education as usual. Our primary study population is the vulnerable subgroup with a Strengths and Difficulties Questionnaire (SDQ) total difficulties score > 80% percentile at baseline (approximately 400 pupils). The primary outcome is change in the SDQ total score by the pupils. We also evaluate the effectiveness among the total pupil study population and in girls and boys, respectively and use other measures on mental health. Data will be analysed with repeated measurement models taken clusters into account. Discussion This large-scale trial will estimate the effectiveness of a population-based strategy on mental health in Danish schoolchildren. The trial evaluates the effect of a school teacher training programme, where teachers are trained in teaching the “.b” programme. The “.b” programme will be taught as a part of compulsory class room teaching. The intervention takes implementation issues into account. Effectiveness will be evaluated both in a vulnerable subgroup and among the total population. Trial registration number ClinicalTrials.gov Identifier: NCT04208113, registered December 23 2019, https://clinicaltrials.gov/ct2/show/NCT04208113.

Aims: We aimed to investigate associations between mental health and sociodemographic characteristics among schoolchildren in Denmark. Methods: We performed a cross-sectional survey from January to October 2019 among 4th to 9th graders ( N=1247) based on pilot data from a nationwide research project Stress-free Everyday LiFe for Children and Adolescents REsearch (SELFCARE). We assessed mental health using the five-item World Health Organization Well-Being Index and the self-report version of the Strengths and Difficulties Questionnaire. We investigated associations between mental health and sex, age in terms of grade, type of school, family setting and geographic region using regression analysis. Results: Mental health was poorer among girls in the older classes compared to girls in 4th grade, and better among boys in the older classes compared to boys in 4th grade. We found no difference in mental health among schoolchildren in municipal and private schools. Mental health was poorer among both girls and boys living alternately with their parents compared to residing with both of them. Mental health varied across geographic regions. Conclusions: We found associations between mental health and sex, age in terms of grade, family setting and geographic region.

Background Mental health is decreasing among young people in Denmark. Our primary aim is to evaluate the effectiveness of a teacher training programme to teach mindfulness as part of regular classroom teaching in Danish upper secondary schools and schools of health and social care on students’ self-reported mental well-being 6 months from baseline. Secondary aims are (1) to evaluate the effectiveness in a vulnerable subgroup as well as in the total population of students 3 and 6 months from baseline using other outcome measures on mental health and (2) to investigate the facilitators and barriers among teachers to implement mindfulness in schools. Methods This pragmatic cluster-randomised two-arm superiority trial includes 30 upper secondary schools, 13 schools of health and social care, 76 teachers, and approximately 1100 students aged 16 to 24 years. Our intervention is multi-level and consists of (a) a teacher training programme and (b) a mindfulness programme delivered to students. Students in control schools receive education as usual. Our primary study population is the total population of students. The primary outcome is changes in the short version of the Warwick-Edinburgh Mental Well-Being Scale (SWEMWBS). We also evaluate the effectiveness in a vulnerable subgroup (the 15% with the lowest SWEMWBS score), as well as in the total population of students 3 and 6 months from baseline using other outcome measures on mental health. Data will be analysed using repeated measurement models taking clusters into account. Facilitators and barriers among teachers to implement mindfulness in schools will be investigated through qualitative focus group interviews. Discussion The trial will estimate the effectiveness of a population-based strategy on mental health in Danish young people enrolled in education. Trial registration ClinicalTrials.gov NCT04610333. Registered on October 10 2020.