Abstract: Background: Great heterogeneity exists in studies on the relationship between adolescents' mental health and 24-h movement consisting of sleep, sedentary behavior, and physical activity. Therefore, it is difficult to obtain high-quality evidence synthesis sufficient to guide clinical practice. Objective: To summarize and evaluate the current status of research on the relationship between 24-hour movement (sleep, sedentary behavior, and physical activity) and mental health in children and adolescents, as well as the problems in research design, so as to provide a reference for future research. Design: Scoping review. Methods: PubMed, Embase, Web of Science, and CNKI databases were searched from the inception to September 28, 2022, with the keywords of sleep, sedentary behavior, physical activity, 24-h movement, mental health, and adolescents to identify research on the correlation or causal inference between 24-h movement and mental health in healthy children and adolescents. Data extraction forms for movement type, measurement methods, classification of measurement items, and specific item measurement were gradually refined in the process of data extraction and synthesis after reading the text title, abstract, and full text for screening. Main outcome measures: Study types and measurement instruments for the relationship between 24-h movement and mental health in adolescents. Results: A total of 927 articles were retrieved from the English and Chinese databases, and after de-duplication, initial screening and full-text screening, 55 articles were finally included with 45 (82%) cross-sectional studies and 10 prospective cohort studies; 47 (85%) subjective reports and 8 objective monitoring articles. For sleep, 54 described sleep duration and 4 assessed sleep quality, sleep latency, daytime sleepiness, and sleep disruption. For sedentary behavior, there were 50 subjective reports, 5 objective reports, and 46 studies about screen exposure. For physical activity, hours of moderate-to-vigorous physical activity were assessed in 47 subjective reports and 8 objective reports. A total of 32 studies focused on depression, 9 on anxiety, 5 on stress, and 35 on other mental health outcomes (positive mood, behavioral problems, life satisfaction or health-related quality of life, mental illness and symptoms, emotion regulation skills, and cell phone addiction). Forty-four papers explored the correlation between 24-h movement and mental health, 8 papers explored changes in the structure of 24-h movement using isochronous substitution models, and 3 explored mediators of 24-h movement affecting mental health. Conclusions: There are few studies on the association between 24-h movement and mental health in adolescents, and the measurement tools used need to be standardized. In the future, isochronous substitution models or real-world intervention studies are needed to find the recommended 24-h movement packages that can maximize the health effects of the movement and are easy to achieve at the same time.

Key words: Adolescents, 24-h activity, Sleep, Sedentary behavior, Physical activity, Mental health