Sleep disorders such as apnea, or any condition causing sleep deprivation in children, can raise the risk for obesity by early adolescence, researchers say.

That's the result of an analysis on data from around 1,900 children in England who were followed by researchers in a study lasting 15 years.

Children who got the least hours of sleep at ages 5 and 6 -- anything less than 10.5 hours is considered insufficient -- had a 60 percent to 100 percent increased risk of being obese at age 15, the researchers found.

Children in the study had their body mass index (BMI) evaluated at age 7, 10 and 15.

"In recent years, lack of sleep has become a well-recognized risk for childhood obesity," says lead study author Karen Bonuck at the Albert Einstein College of Medicine of Yeshiva University in New York.

"When you don't get enough sleep it interferes with the production of hormones that are associated with weight and appetite," she says.

"Sleep-disordered breathing, or SDB, which includes snoring and sleep apnea, is also a risk factor for obesity but receives less attention," she added.

Children with the most severe cases of SDB, abnormal breathing patterns during sleep, had the greatest risk for obesity, she says.

Bonuck says the two risk factors -- lack of sleep or sleep-disordered breathing -- have never been tracked together over time in children to determine their effect on possible weight gain, which is why the current study was initiated.

"If impaired sleep in childhood is conclusively shown to cause future obesity, it may be vital for parents and physicians to identify sleep problems early, so that corrective action can be taken and obesity prevented," she says.

If efforts were made to address each of the risk factors, it could have a significant impact on public health in the United States, where childhood obesity is at around 17 percent, she says.

Some causes of sleep-related childhood breathing problems can be treated, she notes; one common cause is enlarged adenoids or tonsils, which can be corrected with surgery.

Another common cause, a misalignment of the teeth and jaws, can be addressed with orthodontics or a night guard.

"We know that the road to obesity often begins early in life," Bonuck says. "Our research strengthens the case that insufficient sleep and SDB -- especially when present early in childhood -- increase the risk for becoming obese later in childhood."