Before they sleep: Measuring and promoting sleep health in youth

Sleep health has emerged as an important public health issue, particularly among youth. Good sleep health is essential for healthy development and overall well-being, yet many children and adolescents experience unhealthy sleep patterns. Over the past century, global trends have shown a decline in sleep duration and other sleep outcomes among youth, posing a growing public health challenge. Despite its importance, sleep health has received relatively limited attention within public health research and practice. Therefore, the overall aim of this thesis is to improve the measurement and promotion of sleep health in youth, with a specific focus on primary school-aged children and adolescents in secondary education. This thesis demonstrates that, although several promising instruments exist for measuring sleep health in primary school-aged children, the overall quality of evidence regarding their content validity and measurement properties remains inconsistent. While some instruments showed sufficient relevance and comprehensibility, none of the identified instruments were sufficiently comprehensive. In addition, no instrument covered all domains of sleep health. These findings highlight the need for further development and evaluation of measurement instruments to support epidemiological research, intervention evaluation and evidence-based policy making. Additionally, this thesis identified several factors associated with sleep reduction and sleep duration among adolescents. Girls and older adolescents were more likely to experience sleep reduction, partly explained by higher levels of cognitive/emotional and behavioral arousal before bedtime, whereas caffeine use partly explained sleep reduction among boys. Furthermore, more positive attitudes, stronger perceived subjective norms from parents, greater perceived behavioral control, and stronger intentions regarding healthy sleep practices were associated with longer sleep duration. These associations were partly explained by sleep hygiene practices, particularly behavioral arousal before bedtime. Together, these findings highlight the importance of promoting sleep health among adolescents, particularly within girls and older adolescents. Social-cognitive determinants and cognitive/emotional and behavioral arousal before bedtime emerge as targets for interventions aimed at improving adolescent sleep health. Furthermore, this thesis emphasizes the importance of considering the broader socioenvironmental context in which sleep occurs. Lastly, this thesis demonstrates that the school-based intervention Charge Your Brainzzz is a promising first step toward promoting adolescent sleep health. The intervention improved adolescents’ knowledge, attitudes and perceived behavioral control regarding healthy sleep practices, but did not lead to improvements in sleep hygiene practices or sleep outcomes. Overall, teachers considered the intervention feasible and relevant, although they also identified challenges related to implementation such as limited time in the curriculum, compatibility across educational tracks and external socioenvironmental influences on sleep health. Students reported moderate satisfaction with the intervention, with variation across educational tracks. These findings indicate that, while the intervention is a promising starting point, further improvements are needed. Achieving meaningful and lasting effects on sleep outcomes will require better alignment with the needs of both adolescents and teachers through co-creation, as well as integration into a comprehensive systems-based approach.