More Sleep, Less Childhood Obesity
Skimping on Sleep May Make Children More Likely to Become Overweight or Obese
Feb. 12, 2008 -- Getting more
sleep may help children avoid becoming
overweight or obese.
That's according to a new review of 17 studies on sleep and
The studies stretched from Europe to the U.S. to Asia. And around the world,
the pattern was the same: Kids who didn't sleep enough were more likely to be
overweight or obese.
Reviewer Youfa Wang, MD, PhD, an associate professor in the Center for Human
Nutrition at Johns Hopkins University's Bloomberg School of Public Health,
offers these tips for parents:
- Remove the TV, computer, and video games from kids' bedrooms.
"Therefore, children can have more time to sleep rather than be tempted to
engage in these activities," Wang tells WebMD.
- Set earlier bedtimes for kids. Wang suggests reading to young kids
to help them get to sleep earlier.
- Beat the morning rush by preparing the night before. That way, the
whole family can sleep a little bit later.
- Be a good role model for diet and
exercise -- childhood obesity isn't just about sleep.
The review appears in February's edition of Obesity.
Children's Sleep: How Much Is Enough?
The new review used the following benchmarks for kids' sleep, including naps
and nightly sleep, during a typical day:
- Younger than 5: at least 11 hours
- Ages 5-10: at least 10 hours
- Ages 10 and older: at least 9 hours
Those thresholds, which are based on previous research, may not apply to
"Some people, because of their own biological differences or their
quality of sleep, may need fewer hours of sleep than others," Wang tells
Studying Childhood Obesity and Sleep
In the reviewed studies, parents reported how long their young kids slept.
Adolescents reported their own sleep habits.
Wang's team pooled all that data and compared it to the children's BMI (
body mass index), which relates height to
Compared with kids who got enough
sleep, those who fell at least two hours short of the sleep benchmarks were
almost twice as likely to be overweight or obese.
Children who missed the sleep benchmark by an hour were 58% more likely to
be overweight or obese than kids who got enough sleep.
"For each hour increase in sleep, the risk of overweight/obesity was
reduced on average by 9%," the researchers write.
Why the Findings?
The reviewed studies were observational, so it's not clear which came first:
extra pounds or less sleep.
It's also not clear how sleep affects
children's weight. But Wang notes several theories:
- More time awake means more time to eat.
- Less sleep at night makes for drowsier, less-active days (and fewer
- Sleep shortfalls may affect certain hormones. "This may increase
people's feelings of
hunger and also affect their energy expenditure," Wang says.
The links between sleep and BMI were stronger for boys than girls. The
reason for that isn't clear, Wang says.