Study Objectives: To use theory to design and evaluate an intervention to promote sleep hygiene and health among adolescents.

Methods: The Theory of Planned Behavior (TPB) and the Health Action Process Approach (HAPA) were used to develop an intervention, which was then evaluated in a cluster randomized trial. Participants were high school students (N = 2,841, M age = 15.12, SD = 1.50). Adolescents in the intervention group received four face-to-face sessions providing behavior change techniques targeting the theoretical determinants of sleep hygiene. Adolescents in the control group only received educational material at the end of the study. The primary outcome was sleep hygiene measured at 1 and 6 months postintervention. A number of secondary outcomes were also measured, including beliefs about sleep, self-regulatory processes, and outcomes related to health and wellbeing.

Results: Sleep hygiene was improved in the intervention group when compared with the control group at both follow-up points (coefficients = 0.16 and 0.19, 95% CIs = 0.12-0.20 and 0.15-0.23 at 1 and 6 months, respectively, for scores on the Adolescent Sleep Hygiene Scale), as were psychosocial and general aspects of health. Mediation analyses suggested that beliefs about sleep hygiene as specified by the TPB, along with self-regulatory processes from HAPA, both mediated the effect of the intervention on outcomes. In turn, the effects of the intervention on sleep hygiene mediated its impact on general health.

Conclusions: Healthcare practitioners might consider intervention programs based on the TPB and the HAPA to improve sleep among adolescents.

Clinical Trial Registration: Clinicaltrials.gov (NCT02551913) https://clinicaltrials.gov/ct2/show/NCT02551913.