Process Evaluation of a School-Based Intervention Promoting Sleep Health in Adolescents: A Mixed-Methods Study

Background: Poor sleep health is increasingly recognized as a public health issue. Despite the potential of school-based interventions, few have successfully improved adolescent sleep health. To enhance intervention effectiveness, feasibility, and relevance, it is essential to understand barriers and facilitators affecting the adoption, implementation, and sustainment. This study evaluates these aspects for the sleep health promoting school-based intervention Charge Your Brainzzz in Dutch secondary schools. Methods: We conducted 12 semistructured interviews with teachers from five implementation schools, complemented by 372 questionnaires completed by second- and third-grade students from various educational tracks. Qualitative data were thematically analyzed and quantitative data were analyzed using descriptive statistics and tests. Results: Adoption was supported by teachers who valued sleep education and considered it a responsibility of schools. The intervention was generally well implemented, engaging, and aligned with teacher competencies and school structures. However, teachers questioned whether it would sufficiently improve adolescents' sleep health and questioned the intervention's optimal compatibility across educational tracks and grades. Adolescent satisfaction was moderate, showing differences among educational tracks. Implications for School Health Policy, Practice, and Equity: Involving stakeholders through participatory co-creation is recommended to better address adolescents' diverse needs. Given the strong influence of the (social) environment on sleep, expanding Charge Your Brainzzz into a broader, systems-oriented approach could yield greater and more lasting impact. Conclusions: This study provides insights into the adoption, implementation, and sustainment of Charge Your Brainzzz. While well received, further co-creative tailoring and a broader systems approach are needed to improve its impact on sleep health. Trial Registration: ISRCTN36701918.