Sleep Quality as a Mediator Between Lifestyle and Cognitive and Agentic Student Engagement: A Structural Equation Modelling Approach

This study examines relationship between lifestyles and sleep quality, and the subsequent association with levels of school engagement. 1065 Italian secondary school adolescents were involved in the study, and the data were analysed using a structural equation model in R (4.4.0), with the support of the lavaan (0.6.19) package. The model assesses the direct and indirect effects of four exogenous variables (evening consumption of tryptophan-rich foods, vigorous physical activity, the presence of electronic devices in the bedroom, and turning them off before sleep) on cognitive and agentic engagement, with sleep quality as a mediator. The model fit is excellent (CFI = 0.975, TLI = 0.980, RMSEA = 0.034 [90% CI 0.031-0.038], SRMR = .050). Vigorous physical activity and the number of devices switched off before sleep were found to be significant predictors of sleep quality, which mediates the relationship between these factors and engagement. In contrast, evening diet and the mere number of devices present in the bedroom were not significant. The theoretical and practical implications of the study are discussed.