(Good Medical Health) – A new study suggests that only one in 20 children and adolescents in the US benefit from the amount of sleep, exercise and screen time they need for optimal health.

Children and teens are expected to do at least an hour of moderate to vigorous physical activity each day and limit the time spent in front of a screen to less than two hours. Children ages 6 to 12 also need 9 to 12 hours of sleep, while teenagers need 8 to 10 hours a night.

Too little sleep or physical activity, or too much time in front of the screen, can increase the risk of chronic health problems. These include obesity, mental health issues such as anxiety and depression, poor school performance and unhealthy behaviors such as smoking and alcohol, the study team noted in JAMA Pediatrics.

Taken in isolation, these recommendations have been difficult to achieve for many children and adolescents and physicians have been aware of this problem for a long time, said the study's lead author, Gregory Knell, of the Center's Science Center. the health of the University of Texas at Dallas.

"Our study, however, analyzed the prevalence of compliance with ALL three of these recommendations simultaneously," Knell said via email. "This is important because it is proven that not spending the optimal time in the three behaviors has a more pronounced effect on health outcomes than not spending the optimal time in any of the behaviors, regardless."

For this study, researchers examined data on 59,397 children and adolescents who participated in national surveys in 2011, 2013, 2015 or 2017.

Overall, only 3% of girls and 7% of boys spent the optimal amount of time sleeping and being physically active while limiting the time spent in front of the screen.

Compared to participants aged 14 and under, 16-year-olds were 23% less likely to sleep well, exercise, and screen, while 17-year-olds were more likely to 46% lower.

Non-white youth were also less likely than their white counterparts to achieve the three goals: Black children and adolescents had lower odds of 69%; Asian youth had 63% less chance and Hispanic youth 33% less.

Obese youth were 43% less likely to reach all three targets than children with a healthy weight, while overweight children were 20% less likely to manage this.

The study was not designed to examine why young people do not get enough sleep or do not do enough physical activity, or why they spend too much time looking at screens. The study also does not know whether the non-achievement of the three objectives is due to the absence of one or all of the recommendations.

"Lack of physical activity, time spent in front of a screen, and insufficient sleep increase the risk of weight gain and obesity," said James Gangwisch, a researcher at Columbia University Medical Center in New York City. did not participate in the study.

"Similarly, if someone is already overweight, then it might be more difficult to exercise vigorously," Gangwisch said by e-mail. "The lack of adequate physical activity also makes it more difficult to get adequate sleep."

The study was also not designed to demonstrate whether, or how, failure to achieve all three objectives could have a direct impact on physical or mental health.

However, the results suggest that many parents have more work to do to encourage children to rest and exercise and to spend less time watching screens, said Asheley Skinner, researcher at Duke University of Durham, North Carolina, who was not involved. in the study.

Schools can also be part of the problem because they start too early to allow teenagers to get enough sleep, Skinner said via e-mail.

"Sleep and physical activity are two pillars that should not be sacrificed in childhood," said Jonathan Mitchell of the Children's Hospital of Philadelphia and the University of Pennsylvania.

"Too often, sleep is sacrificed for other activities," said Mitchell, who was not involved in the study, by e-mail. "Parents and teens need to think more carefully about daily routines that allow for sufficient physical activity and nighttime sleep. Reducing the time spent in front of a screen and setting bedtime can help you. "

SOURCE: bit.ly/2GngD5w JAMA Pediatrics, online February 4, 2019.