Canadian researchers have found a link between sleeping problems in children and obesity.

The study by researchers at Universite de Montreal found that 26 percent of children who sleep fewer than 10 hours a night become overweight by age six.

Between the ages of six months and six-years-old, close to 90 percent of children have at least one sleep-related problem, with night terrors, teeth-grinding and bed-wetting among the most common issues.

For most children, these problems are simply a stage that passes. But at least 30 percent of children in this age group have difficulties sleeping six consecutive hours, either because they can't fall into slumber or they can't stay asleep. While the effects of lack of sleep on learning are well documented, the Canadian researchers found sleepless children can become overweight and hyperactive.

Jacques Montplaisir, a professor in the Department of Psychiatry and director of Sleep Disorders Centre at Sacré-Coeur Hospital, said that 26 percent of children that sleep fewer than 10 hours a night between two-and-a-half years and six years are overweight. The figure drops to 15 percent of those that sleep 10 hours and falls to 10 percent among those that sleep 11 hours.

The Montreal research team analysed a sample of 1,138 children and found: 26 percent of kids who didn't sleep enough were overweight, 18.5 percent carried extra weight, while 7.4 percent were obese. They say the relationship between sleep and weight could be explained by a change in the secretion of hormones that is brought on by lack of sleep.

Professor Montplaisir says that when we sleep less, our stomach secretes more of the hormone that stimulates appetite, and we also produce less of the hormone whose function is to reduce the intake of food. He says naps do not compensate for nightly lack of sleep.

The study also found that a lack of sleep could also lead to hyperactivity. Twenty-two percent of children who slept fewer than 10 hours at age two and a half suffered hyperactivity at six-years-old, which is twice the rate seen in those who slept 10 to 11 hours per night.

Professor Montplaisir says that while it could be assumed from the figures that hyperactive children sleep less, it is actually a case of under-slept children becoming hyperactive.

"In adults, inadequate sleep translates into sleepiness, but in children it creates excitement," he says.

© NewsRoom 2008