A growing body of research and official reports has documented a negative trend in the well-being of children and young people (Inchley et al., 2020; Public Health Agency of Sweden, 2014, 2018). However, far less is known about how well-being develops within individuals over time, particularly across key educational transitions such as the move from lower to upper secondary school. Longitudinal research examining multiple dimensions of well-being during adolescence is therefore needed to generate deeper insights that can inform interventions aimed at promoting children’s and young people’s well-being.

Supporting this perspective, a systematic review by Donaldson et al. (2023) shows that challenges encountered during transitions between educational stages can have long-lasting effects on academic achievement, self-concept, and trajectories of well-being and health. The authors further emphasize that interventions designed to enhance student well-being should prioritise strengthening relationships among parents, teachers, and peers, as these social connections are critical to their effectiveness.

Given that children and adolescents spend a substantial proportion of their time in school during compulsory education, it is reasonable to assume that changes in well-being are closely linked to school-related factors (Högberg et al., 2019), as well as to individual characteristics.

In the present study, we focus on three central dimensions of well-being: social, psychological, and psychosomatic. Although these dimensions do not capture all aspects of children’s and adolescents’ well-being and mental health, they are widely recognised in the literature as core components. Social well-being concerns supportive and functional interpersonal relationships, with difficulties in this domain linked to social isolation (Pollard & Lee, 2003). Psychological well-being reflects emotional stability and life satisfaction, characterised by low levels of stress and worry. Psychosomatic well-being captures physical symptoms arising from psychological strain, such as headaches, stomach pain, and sleep disturbances (National Agency of Public Health, 2018).

The primary aim of the study was to examine intraindividual development in social well-being, psychological and psychosomatic ill-being over time. This was accomplished using longitudinal data collected at three time points, spanning the transition from lower to upper secondary school (Grades 6, 9, and 12), for a nationally representative cohort of students born in 2004. The study addressed the following research questions:

1. How do social well-being and psychological and psychosomatic ill-being develop over time from Grade 6 to Grade 12? 

2. Are changes in well-being and health constructs related to academic achievement, gender, or the level of parental education?    

In this study, we draw on data from the Swedish longitudinal project Evaluation through Follow-Up (UGU) which consists of representative samples from 11 birth cohorts, born approximately every sixth year between 1948 and 2016. Each sample is about 10% of the population. In the present study, a sample of the birth cohort born in 2004 was analysed when the students attended their sixth (age 12-13), ninth (age 15-16), and twelfth (age 18-19) year of schooling. The sample was drawn when students were in the third grade (age 9-10), using a two-stage stratified procedure. First drawing municipalities and then schools. The total sample consisted of 9,775 students, but with missing observations considered, N = about 5,000 in sixth grade, N = about 2,500 in ninth grade, and N = about 2,000 in twelfth grade. As a first step, an unconditional model was specified for each factor (social well-being and psychological and psychosomatic ill-being), examining the mean change over time. A conditional model was then specified for each factor, including independent time-invariant variables that potentially could explain the growth trajectories of social well-being and psychological and psychosomatic ill-being. Three latent variables were included in the study, each measured on three occasions (in Grades 6, 9, and 12). Three time-invariant manifest variables (GPA, gender, and parental education) were also included. Descriptive statistics, measurement invariance and Confirmatory factor analysis (CFA) were conducted. To examine changes in students’ well-being and ill-being over time, latent growth curve modelling was applied. These models allow us to examine changes in longitudinal data over time by defining one latent intercept variable and one latent slope variable with data from each measurement occasion as indicators (Little, 2024). As a first step, an unconditional model was specified for each factor (social well-being and psychological and psychosomatic ill-being), examining the mean change over time. A conditional model was then specified for each factor, including independent time-invariant variables that potentially could explain the growth trajectories of social well-being and psychological and psychosomatic ill-being.

One of the main findings of the study was a statistically significant intraindividual decline in well-being and mental health over time. Social well-being, reflected in satisfaction with social relationships at school, decreased across the study period, while psychological and psychosomatic ill-being increased. Specifically, students reported growing levels of low mood, irritation, and sadness, as well as increasing problems related to stomachaches and sleep disturbances. Gender and parental education emerged as important correlates of these developmental patterns. Compared with boys, girls reported lower levels of social satisfaction at school and consistently higher levels of psychological ill-being throughout both lower and upper secondary school. Girls also experienced more psychosomatic complaints, including headaches, stomachaches, and sleep problems, with these gender differences widening over time. In addition, students from families with lower levels of parental education reported persistently higher levels of psychological and psychosomatic ill-being compared with peers from more highly educated families. Taken together, the findings suggest that girls and students from families with lower educational backgrounds are at heightened risk of declining well-being and mental health throughout their school years.

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