Compositional Associations of Time Spent in Sleep, Screen Time, and Physical Activity with Polysubstance Use in Adolescents
Purpose: The purpose of this study was to examine the relationship between the movement behavior composition (time spent in sleep, screen time, and physical activity) and polysubstance use in adolescents. Methods: This cross-sectional study examined 14,701 Canadian adolescents in grades 6-10. The independent variable was the composition of time spent in physical activity, screen time, and sleep. The dependent variable was high polysubstance, a composite measure reflecting the frequency of using cigarettes, alternative tobacco products, alcohol, cannabis, and illicit drugs. Compositional data analysis was used to investigate relationships between the movement behavior composition and its components with high polysubstance use. Compositional isotemporal substitutions estimated how relocating time from one movement behavior to another changed the risk of high polysubstance use. Results: The movement behavior composition was significantly associated with high polysubstance use (p<0.001). In grades 6-8 students and grades 9-10 girls, relative time in sleep was negatively associated with high polysubstance use whereas relative time in screen time was positively associated with high polysubstance use (p<0.01). Time displacement estimates in grades 6-8 students and grades 9-10 girls showed that reallocating equal time from physical activity or screen time into sleep was associated with a lower risk of high polysubstance use. In grades 9-10 boys, removing 60 minutes/day from physical activity and reallocating it into screen time or sleep was associated with an increased risk of high polysubstance use. Conclusion: The movement behavior composition and movement behavior time displacements were associated with high polysubstance use.