Children who get too little sleep may be more likely to have risk factors for type 2 diabetes, new research suggests.
The study of more than 4,500 British kids found a link between kids' sleep habits and certain diabetes "risk markers." Children who slept fewer hours each night tended to be a bit heavier and to show more insulin resistance.
Insulin is a hormone that regulates blood sugar levels. When the body starts to become resistant to insulin, that can be a precursor to type 2 diabetes.
So, the findings raise the possibility that childhood sleep habits could affect the odds of diabetes -- or other health conditions -- later in life, said researcher Christopher Owen.
"We believe that these small differences [in diabetes risk markers] early in life could plausibly persist," said Owen, a professor of epidemiology at St. George's, University of London.
Past studies, he noted, have found that diabetes risk can "track" from early life to adulthood.
However, the new findings do not prove that a lack of sleep causes kids' diabetes risk to rise, said Dr. Nicole Glaser.
Glaser, a pediatrician and professor at the University of California, Davis, cowrote an editorial published online with the study in the Aug. 15 issue of Pediatrics.
In it, she points out that there could be other explanations for the link between kids' sleep and diabetes risk markers: For example, it might reflect differences in the brain functions that regulate sleep, appetite and insulin sensitivity.
"It's not yet clear whether the association between sleep and obesity/ type 2 diabetes risk is a causative one," Glaser said.
Still, "there is really no 'downside' to making sure your children get enough sleep," she added.
"There are studies to suggest that adequate sleep is necessary for optimal learning and memory, and that getting adequate sleep has beneficial effects on mood," Glaser said.
Dr. Mercedes Bello directs the sleep disorders center at Nicklaus Children's Hospital in Miami.
She said it's plausible that inadequate sleep could directly affect children's weight and insulin resistance, since sleep influences the release of various hormones.
Bello agreed that the latest findings do not prove that later bedtimes boost kids' diabetes risk. She called the study a "good start" to try to answer that question.
For now, Bello had advice for parents on helping school-age kids get enough sleep: Turn off the TV and electronic devices about an hour before bedtime, since the blue light can disrupt sleep. Limiting liquids close to bedtime -- and caffeine, in general -- can also help, she said.
According to the National Sleep Foundation, children aged 6 to 13 should get nine to 11 hours of sleep each night.
The new findings are based on 4,525 children from the United Kingdom, aged 9 and 10, who were asked about the usual bedtimes and rising times on school days. The researchers measured the kids' weight, height and body fat, and took blood samples to test their insulin and blood sugar levels.
On average, the study found, the children were getting 10.5 hours of sleep each night -- solidly within the recommended amount.
Still, there was a wide range in sleep habits: Some kids got only eight hours of sleep a night, while others typically got 12.
Overall, the study found, long sleepers tended to be a bit thinner and have less insulin resistance.
An extra hour of sleep, for instance, correlated with a 3-percent reduction in insulin resistance and a 0.2-point lower body mass index. (BMI is a measure of weight in relation to height.)
Those are small differences, Glaser said. But, she added, the numbers are averages across a group: It's possible that for some kids, the association between sleep and diabetes risk factors is "more pronounced."
Owen's team did dig into some other potential explanations for the findings: Were physically active kids prone to sleeping more, for instance?
But exercise did not explain the results, the researchers said. Nor did the family's socioeconomic situation -- which could affect kids' lifestyle habits and health.
According to Owen, the findings suggest that extra sleep could be a "simple, cost-effective approach to reducing body fat and type 2 diabetes risk from early life."
But the only way to really test that, Glaser said, is with "intervention" studies -- where researchers would, somehow, get kids to sleep more.topics from