New research suggests that the amount of exercise children get each day corresponds to the amount of available daylight -- and that daylight savings time could have a notable impact of kids' health.
When days are shorter, as they are in in fall and winter, kids are less likely to be active. Not exactly surprising, but significant from a policy perspective.
"The more kids are outside enjoying what little daylight they have, the better off they're going to be," Geoff Glaster, a father of two, told CBS. Glaster says it's common sense, not science.
But for researchers at London School of Hygiene and Tropical Medicine, it is science.
They looked at the exercise habits of 23,000 children, ages 5 to 16, from nine countries -- including the United States, England, Australia, Norway, Denmark, Estonia, Switzerland, Brazil and Portugal. They found kids' activity levels spiked in the summer, when sunlit evening hours are more plentiful. More daylight hours see kids exercise 15 to 20 percent more than they do in the winter.
"This study provides the strongest evidence to date that, in Europe and Australia, evening daylight plays a role in increasing physical activity in the late afternoon and early evening -- the 'critical hours' for children's outdoor play," study author Anna Goodman explained in a press release.
With each loss of a daylight hour, researchers found, kids' activity levels drop 5 percent. That's what will happen in the United States on Sunday when clocks fall back -- which means a chance to sleep in, but also less playtime after school.
If may not seem like a lot, but scientists say just a little bit more exercise each day could go a long way.
Diabetes and obesity remain two of the West's most widespread public health problems. In addition to getting kids to eat healthier, encouraging more play and exercise is one of the most important to curb these two problems early -- before unhealthy habits are solidified as kids become adults.
The work of Goodman and her colleagues was detailed this week in the International Journal of Behavioral Nutrition and Physical Activity.