Inadequate sleep affects the carbohydrate metabolism in children and caused impaired glucose tolerance. This in turn affects the secretion of hormones that regulate fat storage. All these factors may work in combination to increase weight in children, the study found.

The researchers used data from National Institute of Child Health and Human Development Study of Early Child Care and Youth Development. Almost 785 elementary school children were involved in the study. All children were aged 9 to 12 years.

81 percent of the children studies were while, while 50 percent were male, the background information on the study states. The researchers examined the existence of any link between inadequate sleep and overweight for third-grade and sixth-grade children.
The researchers found that overweight children in the sixth grade got fewer hours of sleep than children who were not overweight. However children who had sleep problems were not found to be at risk of being overweight.

“This study suggests that an increased risk for overweight is yet another potential consequence of short sleep duration, providing an additional reason to ensure that children are receiving adequate sleep, primarily through enforcing an age-appropriate bed time," lead author Julie C. Lumeng, M.D., assistant research scientist at the U-M Center for Human Growth and Development.

Every additional hour of sleep in the third grade meant that children were 40 percent less likely to be overweight. In the sixth grade every additional hour of sleep was associated with a 20 percent decreased risk of gaining weight.

The National Sleep Foundation recommends that children, adolescents, pre-teens and teens get the following hours of sleep everyday:

• Preschoolers: 11-13 hours
• Elementary school students: 10-12 hours
• Pre-teens: 9 - 11 hours
• Teens: 8 ½ - 9 hours

The details of the study appear in the November issue of the journal Pediatrics.

Overweight and obesity are an increasing problem among children worldwide. The National Health and Nutrition Examination Survey (NHANES), conducted during 2003-2004 had revealed an alarming increase in child obesity rates. Around 33.6 percent of children and adolescents were overweight as found by the survey as compared with 16 percent in 2002.

Sedentary lifestyle practices coupled with a shift in diet to junk foods are the main reason behind this explosion of overweight or obese children. Now researchers have also identified lack of sleep as being a contributory factor to childhood obesity.