Well under 10% acheived all three recommended goals

by Elizabeth Hlavinka, Staff Writer, MedPage Today February 05, 2019

Hardly any adolescents met recommendations for sleep, physical activity, and screen time exposure, federal survey data from 2011-2017 indicated.

Among nearly 60,000 teens from the Youth Risk and Behavior Surveillance Survey, just 7% of boys and 3% of girls met recommendations for all three factors, and overall, just 5% did (95% CI 4.6%-5.4%), reported Gregory Knell, PhD, of UTHealth School of Public Health in Dallas, and colleagues.

Compared to kids 14 or younger, 16-year-olds were about 23% less likely to get the proper amount of sleep, screen time, and physical activity, and 17-year-olds were 46% less likely, they wrote in JAMA Psychiatry.

While the effects of sleep, screen time, and physical activity on health behaviors have been extensively studied independently, their cumulative effects have not been researched as thoroughly, Knell told MedPage Today.

Knell and colleagues drew their benchmark goals for the three behaviors from recommendations in 2009 that children ages 6-12 sleep 9 to 12 hours per day and teens ages 14-18 sleep 8 to 10 hours per day; children of all ages should have at least 1 hour of moderate or vigorous exercise; and they should limit screen time to no more than 2 hours per day.

However, a 2016 study found the average 8- to 10-year-old was spending about 8 hours per day using media and older kids more than 11 hours. Another report indicated 73% of high school students and 58% of middle school-age children were not getting the recommended sleep. And a third study from 2015 showed children were getting less than 40 minutes of daily exercise, on average.

The current study drew on the Youth Risk Behavior Surveillance Survey's cross-sectional data from its 2011, 2013, 2015, and 2017 cycles, stratified by age, race/ethnicity, body mass index, risky behaviors (alcohol, tobacco, and marijuana use), asthma diagnosis, and depressive symptoms. (That these data were largely self-reported was an important limitation of the study, Knell and colleagues acknowledged.)

In total, 58,397 teenagers ages 14-18 were included in the study, of whom 56% were non-Hispanic white, 14.1% non-Hispanic black, 22% Hispanic, 3.5% non-Hispanic Asian, and 6.2% "other." One-quarter to one-third of participants were obese, asthmatic, or had depressive symptoms. About 20% used tobacco, 35% used alcohol, and 23% used marijuana, according to the study.

Compared to non-Hispanic white teens, all other races were significantly less likely to meet the guidelines for physical activity, sleep duration, and screen time. Odds ratios relative to whites were 0.31 for non-Hispanic blacks, 0.66 for Hispanics, and 0.37 for non-Hispanic Asians.

Those in the sample who used marijuana were less likely to achieve the recommendations for all three factors (OR 0.81, 95% CI 0.69-0.96), as were those reporting depressive symptoms (OR 0.44, 95% CI 0.38-0.50). Girls, but not boys, reporting alcohol use also tended to miss the guideline goals (OR 0.72, 95% CI 0.56-0.93), the authors reported.

And participants who were overweight and obese were less likely to achieve the recommended amount of sleep, physical activity, and screen time compared to children of normal weight (20% and 43%, respectively).

Screen time in young children has been associated with developmental issues, while physical activity has been shown to improve children's cardiometabolic risk profile and lack of sleep has been linked to depression in adolescents. Their cumulative effects on overall health could be even more substantial, Knell told MedPage Today.

Although this study did not examine what these effects were, Knell said understanding the prevalence of this issue is an important first step.

"What we're starting to learn is these behaviors occurring simultaneously have a larger effect on health outcomes than any one independently," he said.

The study was financially supported through a postdoctoral fellowship at the University of Texas School of Public Health Cancer Education and Career Development Program supported by the National Cancer Institute/National Institutes of Health.

No other relevant disclosures were reported.