The Trajectory of Sedentary Behavior from Adolescence to Emerging Adulthood


Alert, Marissa D. (2017). The Trajectory of Sedentary Behavior from Adolescence to Emerging Adulthood.


US adolescents spend up to 8 hours daily in screen time. Efforts to reduce sedentary time have often focused on identifying its correlates. However, little is known about the trajectory of adolescents’ screen time or factors that predict it. This study examined change in screen time from age 13 to 23 and its predictors in a representative US sample. Adolescents (N = 3,705; 46.3% boys) from the National Longitudinal Study of Adolescent to Adult Health’s public-use data self-reported their screen time (hours/week watching TV and videos, and playing video/computer games) in 1994, 1996, 2001 and 2008. Piecewise latent growth models within a cohort-sequential design modelled screen time from ages 13-18 and 19-23 years. Predictors of change for each piece of the model were gender, parental education and limits on screen time, household income, perception of neighborhood safety, race/ethnicity, BMI, physical activity (PA) and employment status. Results indicated that adolescents spent an average of 24.99 hours/week in screen time at age 13 and > 14 hours/week until age 23. Screen time decreased 1.27 hours per week per year from age 13 to 18 then increased .39 hours per week per year from age 19 to 23 (ps < .001). From 13 to 18, decrease in screen time was associated with feeling safe in the one’s neighborhood (b = 2.70, p = .01), having parental limits on screen time (b = 1.22, p = .02), and being Asian American (vs. whites; b = 2.27, p = .02). From 19 to 23, African Americans (b = -1.13, p < .001) and Asian Americans (b = .67, p = .04) had a lower increase compared to whites. More bouts of PA were also associated with lower increase in screen time (b = -.04, p = .03) during emerging adulthood. Participants who were only in school (b = .43, p = .01) or neither in school nor working (b = .91, p < .001) had a greater increase in screen time than those who were only working. Interestingly, screen time increased after the age of 18, a point when many transitions, such as the entry into college, often occur. However, given the high levels of screen time maintained from ages 13 to 23, effective means of curbing screen time during these developmental periods are needed. Focusing on modifiable factors such as parental limits on screen time and physical activity may help to curb this behavior. Since the factors associated with change in screen time from ages 13-18 and 19-23 differed, this may be important to consider when developing interventions to reduce sedentary behavior.



sedentary behavior

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Alert, Marissa D.

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University of Miami

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