I recently came back from Utah, visiting the folks at Utah Public Radio and doing some speaking around the Beehive State. Utah has the lowest rate of smoking in America because so many of the people there think smoking is dumb. This idea comes from the Mormon Church, which is a strong player in many aspects of Utah life.

The people of Utah also are way down on the obesity scale with many seeming to embrace an outdoor way of life, something that it is important for all of us to think about, especially our children.

Last week, I talked about a recent study from the British Medical Journal that showed the more screen time a child has, the more likely they are to be overweight and have insulin resistance and elevated blood sugar, putting them at risk for diabetes. Down with screens, up with exercise.

But before I go on to the exercise study, I’d like to review (be careful, it could be on your pop quiz) the study I discussed last year on kids, screens and sleep.

Kids who look at a screen – computer, TV or smartphone – just before sleep are more likely to have difficulty falling asleep (up to 30 minutes) and staying asleep because the screen time interferes with REM sleep. We know that sleep is critical to a growing child for all sorts of reasons, from growth in adolescence to success in school. Parents who don’t press the off switch on their kids’ personal devices are doing them a disservice. Wake up and smell the coffee, guys!

So on to the exercise study. For many years, we have said that when kids reach adolescence, their outside play time tends to diminish. You remember, or at least I remember, when I was in elementary school I had recess — morning and afternoon recess. It was a great time to go outside and run around.

Teens don’t do that. (Neither do adults, by the way. Perhaps we should all have recess — but that’s for another column.) So the thought has been that the teen years are where exercise begins to drop off.

Well, we were wrong. This BMJ study shows that in our modern technological society, there are so many demands and desires of our kids that active time, when kids are moving their muscles, just might drop off — now, get this — at age 9. You got it, in elementary school.

The study was well-designed, and though it was small, with only 400 kids, it’s well worth discussing. Children ages 7, 9, 12 and 15 wore small, lightweight activity monitors, similar to the ones we adults wear such as the Fitbit, but more scientifically accurate and slightly different. These monitors, called ActiGraphs, were worn all day long for one week, recording physical activity every 15 seconds and plotting that against time.

Here’s the scoop: The 9-year-olds moved less than the 7-year-olds, the 12-year-olds moved less than the 9-year-olds, and the 15-year-olds were the sloths of the group. So while it’s true that adolescents sit around more, this study showed that the activity drop starts much sooner.

But now hear this. An encouraging study out of Wake Forest Medical Center analyzed data from nearly 12,000 kids ages 8 to 18 – in the US, Brazil and European countries giving the kids devices to measure their activity and measuring waistline, blood pressure, good and bad cholesterol. They found that as little as 10 minutes of high-intensity physical activity brought down their blood pressure, cholesterol and other biomarkers that are a risk for heart disease.

My spin: If we put last week’s column about too much screen time together with this week’s column about too little exercise and do the math, the outcome is obvious. Too much screen time and too little activity add up to make Dick and Jane fat and lazy. Stay well.

This column provides general health information and is not specific advice intended for particular individual(s). It is not a professional medical opinion or diagnosis. Always consult your personal health care provider about concerns. No ongoing relationship of any sort (including but not limited to any form of professional relationship) is implied or offered by Dr. Paster to people submitting questions.