U.S. adults aren’t the only people who are gaining weight. The number of children who are overweight also is rising at an alarming rate. There are many causes, but one factor may surprise you: Many U.S. children aren’t getting enough sleep.

The National Heart, Lung, and Blood Institute reports that in the U.S. about 17 percent of children and teens are overweight. This percentage has more than doubled in the past 30 years.

A study in the April 7 issue of the Archives of Pediatrics & Adolescent Medicine examined sleep duration and weight in children. The study involved 915 children. As infants they slept an average of 12.3 hours per day. Infants who slept less than 12 hours per day had a higher body mass index for their age and sex. At three years of age, nine percent of the children had become overweight. Children were more likely to be overweight at age three if they slept less than 12 hours per day as infants.

A study in the journal Sleep in 2008 also found that children who don’t get enough sleep are more likely to be overweight. The study involved 591 seven-year-old children. Results show that the average time spent in bed was 10.1 hours. Children who slept less than nine hours per night were more likely to be overweight or obese.

An article in Pediatrics in 2007 involved 785 children. Results show that shorter sleep duration is linked to a higher risk of being overweight. Overall, 18 percent of the children were overweight in the sixth grade.

A study in Obesity in 2006 shows that overweight children also have a high risk of sleep-disordered breathing. A common form of sleep-disordered breathing is obstructive sleep apnea. Most children with sleep apnea have a history of snoring. The study involved 100 children. They were between seven and 11 years of age. Results show that one in four overweight children suffer from sleep-disordered breathing.

Cognitive and behavioral problems are common in children with sleep apnea. These problems may include:

  • Aggressive behavior
  • Attention-deficit/hyperactivity disorder (ADHD)
  • Delays in development
  • Poor school performance

The following are symptoms of child sleep apnea:

  • Snoring or noisy breathing
  • Pauses in breathing during sleep
  • A rib cage that moves inward as the child inhales
  • Body movements and arousals from sleep
  • Sweating during sleep
  • Sleeping with the neck overextended
  • Excessive daytime sleepiness
  • Hyperactivity or aggressive behavior
  • A slow rate of growth
  • Morning headaches
  • Bedwetting

The American Academy of Sleep Medicine recommends that pre-school children get 11 to 13 hours of nightly sleep. Schoolchildren should get 10 to 11 hours of sleep each night.

It is important to make sure that your child gets enough sleep and sleeps well. If your child has an ongoing sleep problem, then you should talk to your child’s doctor or to a sleep specialist. Help can be found at sleep disorders centers that are accredited by the American Academy of Sleep Medicine. You can find an AASM-accredited sleep center near you.