Between the ages of six months and six years old, close to 90 percent of children have at least one sleep-related problem.
Among the most common issues are night terrors, teeth-grinding and bed-wetting.
For the majority, it's 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, researchers at the Université de Montréal have found sleepless children can become overweight and hyperactive.
Jacques Montplaisir, a professor in the Department of Psychiatry and director of Sleep Disorders Center at Sacré-Coeur Hospital said that 26 percent of children that sleep fewer than 10 hours a night between two and 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 research team analyzed 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.
The relationship between sleep and weight could be explained by a change in the secretion of hormones that's brought on by lack of sleep. "When we sleep less, our stomach secretes more of the hormone that stimulates appetite," Montplaisir explains. "And we also produce less of the hormone whose function is to reduce the intake of food."