Inter-relação entre os indicadores relacionados ao sono, jet lag social, turno de estudo, atividade física, práticas alimentares e medidas antropométricas em adolescentes no município do Rio de Janeiro

Abstract

Sleep, like healthy eating and physical activity, is recognized as essential for well-being in public health guidelines. However, the relationship between chronotype, social jet lag and healthy habits is still poorly understood, especially in adolescence, a crucial phase for establishing lasting habits. The thesis was structured in two articles, with the following objectives: to investigate the influence of chronotype on food practices and explore the interrelationships between chronotype, sleep duration, social jet lag, screen time, physical activity, food practices, and anthropometric measures in adolescents attending morning and afternoon school shifts. This cross-sectional study involved students aged 15 to 19, who completed an online questionnaire covering food practices, sleeping habits, screen time, socioeconomic data, physical activity and anthropometric measurements. Associations between these variables were explored through adjusted logistic regression analyses and structural equation modeling, with six path models in the latter. The first article (n = 734) revealed that morning chronotype adolescents attending morning classes were more likely to have breakfast, compared to evening chronotypes. Both morning and intermediate chronotypes were more likely to have a morning snack and were less likely to consume fast food regularly. In the afternoon shift, morning chronotype was associated with greater chances of having breakfast and consuming beans, vegetables, and fruits. Additionally, the intermediate chronotypes were more likely to have breakfast, have a morning snack, consume vegetables and fruits and less likely to have meals with over 26% of total daily energy intake after dinner. The second article (n = 925) found that, among morning shift students, reduced sleep time was directly associated with higher BMI-for-age, while greater screen time was negatively associated with complete meal practices and physical activity. Among afternoon shift students, a stronger eveningness tendency was linked to lower adherence to complete meal practices and reduced fruit and vegetable intake. Additionally, sleep duration was positively associated with complete meal practices and regular fruit consumption, while greater screen time was associated with unhealthy foods. Physically active adolescents were more likely to consume fruit regularly in both shifts. The findings suggest that food patterns and practices, influenced by chronotype and other variables, are also influenced by the study shift. Poor sleep may directly contribute to overweight. Future longitudinal and intervention studies are needed to further investigate these findings, highlighting the importance of considering both study shift and chronotype in research.