Children who do not get enough sleep or who have sleep-related breathing problems may have an increased risk of becoming obese by the age of 15, a new study suggests.

According to US researchers, in recent years, ‘lack of sleep has become a well-recognised risk for childhood obesity'. Sleep-disordered breathing (SDB) is also seen as a risk factor, but has not been the subject of as much research.

SDB includes snoring and sleep apnoea, a condition in which a person stops breathing many times during their sleep.

"These two risk factors had not been tracked together in children over time to determine their potential for independently influencing weight gain. Our study aimed to fill in that gap," explained the study's author, Prof Karen Bonuck, of the Albert Einstein College of Medicine.

The researchers looked at almost 1,900 children who were taking part in an ongoing study in the UK. They found that those with the worst SDB had the biggest risk of becoming obese. In fact, they were twice as likely to become obese by the age of seven, 10 and 15 compared to their peers without SDB.

When it came to sleep duration, five and six-year-old children who had the shortest sleep duration had a 60-100% increased risk of being obese by the time they were 15. Although, the researchers noted that this risk did not translate to children of other ages who did not get enough sleep.

Short sleep duration at the age of five and six was considered 10.5 hours or less per night.

The researchers noted that while sleep duration and SDB were strong risk factors for obesity, their effects were independent of each other and there was little evidence to suggest that children who had one of these risk factors were more likely to also have the other one.

The study did not look into whether those with both risk factors were at a higher risk of obesity than those with just one of the risk factors.

"We know that the road to obesity often begins early in life. 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.

"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," Dr Bonuck said.

However, she emphasised that these are problems that can be corrected. For example, a common cause of SDB in children is enlarged tonsils, which can be surgically removed. And sleep duration can be improved by learning good sleeping habits.

Details of these findings are published in The Journal of Pediatrics.