1. Introduction
HHS, Stress
REGRESSION, MAY, SECONDARY
Stress is a widespread phenomenon and young people especially are experiencing high levels of stress. School-related factors are the most frequently self-reported stressors among adolescents, but few interventions have targeted the school environment. This study evaluated the effectiveness of the Healthy High School (HHS) intervention on stress at a 9-month follow-up. The study included 5201 first-year high school students (~16 years) in Denmark. Participating schools were randomized into the HHS intervention (N = 15) or control group (N = 15). Baseline measurements were conducted in August 2016 and the follow-up was conducted in May 2017. The intervention was designed to promote well-being (primary outcome) by focusing on physical activity, meals, sleep, sense of security, and stress (secondary outcomes). The intervention comprised: structural initiatives at the school level; a teaching material; peer-led innovation workshops; and a smartphone app. The 10-item Perceived Stress Scale was used to measure stress. Intervention effects on perceived stress were estimated using an intention-to-treat approach with multiple imputations of missing data and multilevel general linear regression modelling. A total of 4577 students answered the baseline questionnaire. No statistically significant difference was found in stress between students at intervention and control schools at the follow-up (mean score: 16.7 versus 16.7, adjusted b = 0.42, 95% CI: −0.16;1.00). The HHS Study is one of the first large randomized controlled trials targeting school environmental stressors. Potential implementation failures and the failures of the program theory are discussed.Stress seems to be a significant worldwide problem and young people especially report high stress levels [The transition to high school is a challenging period for many adolescents as there is a radical shift in school context [Schools are considered as important settings for public health initiatives for children and adolescents. They spend a considerable amount of time at school, and the school provides an opportunity to reach almost everybody within the relevant age group [Internationally, there has been a growing body of studies investigating the effects of educational strategies to prevent stress in school settings. For example, school-based interventions targeting stress management (e.g., problem solving, social skills training, mindfulness, relaxation techniques, and time management) in children and adolescents seem to be effective in reducing stress symptoms, self-reported stress, and cardiovascular parameters of stress (e.g., blood pressure) and in improving coping, academic, and social skills [While educational initiatives focus on individual behavior changes, there are many sources of stress that involve the structure or culture of an organization (e.g., workplace or school) which are less amendable at the individual level [The Healthy High School (HHS) Study was developed to promote well-being (the primary outcome) among first-year high school students (16-year-olds) in Denmark using a combination of educational and environmental initiatives. A thorough needs assessment (literature reviews and quantitative and qualitative research) among the target population identified stress prevention and the promotion of regular meals, physical activity (PA), sleep, and students’ sense of community at school as five important pathways to achieve a higher level of well-being. The purpose of this study was to examine the effects of the HHS Study on students’ perceived stress at the 9-month follow-up. The primary outcome of the trial (well-being) as well as the outcomes of the four other pathways to well-being will be reported elsewhere.