Objectives: The main objectives of this study were to (1) determine whether sex moderates the association between social media use and body mass index (BMI) and (2) assess whether sleep duration mediates the association between social media use and BMI.
Design: A cross-sectional province-wide and school-based survey of 7th to 12th graders (mean age: 15.1 years).
Participants: The sample consisted of 4,991 students from the 2015 cycle of the Ontario Student Drug Use and Health Survey (Canada).
Measurements: Participants self-reported time spent using social media, total screen time, physical activity, sleep duration, and body weight and height. Multiple linear regression analyses were used to examine the association between social media use and BMI z-scores. Given that the sex by social media use interaction term was significant, analyses were stratified by sex.
Results: After adjusting for age, ethnic background, subjective socioeconomic status, frequency of breakfast consumption, and physical activity, heavy social media use (>2 hours/day) was associated with higher BMI z-scores among males (β=0.323, 95% CI: 0.094; 0.551) than among females (β=0.036, 95% CI: -0.292; 0.364). This association remained significant after further adjusting for total screen time. Results also showed that sleep duration mediates the association between social media use and BMI z-scores among men.
Conclusion: Our results showed that short sleep duration is a concurrent mediator of the relationship between social media use and BMI z-scores among males. Reducing time spent using social media may be a good behavioral target to promote adequate sleep duration, which is considered as a component in childhood obesity prevention efforts.
Senior Scientist, CHEO Research Institute