Using mobile assessments to characterize mental and physical health behaviors in youth: the mSanté protocol for a pilot observational intensive longitudinal study

Background: Lifestyle is a key determinant of physical and mental health. Reducing unhealthy behaviors, such as inadequate sleep, physical inactivity, and poor diet among children and adolescents may prevent serious long-term consequences on physical and mental health. However, empirical evidence on the temporal dynamic interrelationships of multiple behavioral health domains is scarce. Here, we describe the protocol of the mSanté pilot study, which examines the temporal relationships between sleep, physical activity, diet, and emotional states in school-aged youth using ambulatory assessments. The objective of the pilot study is to assess the feasibility of prolonged ambulatory assessment within school and clinical samples, and to lay the methodological groundwork for introducing developmental/idiographic models of health behaviors that inform about individual trajectories of risk and resilience.Methods: We aim to collect data from a total of 100 participants aged 9-17 years in diverse school and clinical settings. Beyond baseline information on demographic characteristics, health behaviors, social functioning, medical and psychological health, participants will engage in multiple waves of intensive longitudinal assessments on multiple timescales. These will include continuous actigraphy and Ecological Momentary Assessment (EMA) accompanied by repeated trait-level self-reports. Subsequent analyses will consist of: (1) fragmentation analysis to quantify subject-specific stability; (2) functional principal component analysis using the actigraphy dataset; (3) multilevel regression models to assess specific within-person processes; (4) generalized estimating equations and network modeling to explore the temporal dynamic associations of health behaviors with emotional states.Discussion: This study delves into the developmental dynamics of mental and physical health in emerging adolescence through detailed, longitudinal momentary assessments, providing valuable insights into the interplay between health behaviors during late childhood and adolescence. Despite challenges such as sample bias, the research sets a significant foundation for future large-scale studies aimed at dissecting the complex developmental trajectories of risk and resilience.