Lack of sleep makes children fat

A new study by researchers in the United States has found that children who do not get enough sleep are more likely to be overweight.

The researchers at the University of Michigan's Center for Human Growth and Development, say that not getting enough sleep can interfere with a child's metabolism which in turn can affect their exercise and eating habits; this increases the risk of unhealthy weight gain.

Other research has already demonstrated that adults who do not get enough sleep are at increased risk of obesity and research in Japan and the UK has shown there is a link between insufficient sleep and being overweight in childhood.

Dr. Julie Lumeng, an assistant professor in the Department of Pediatrics and Communicable Diseases at the University's CS Mott Children's Hospital says that those studies did not take into account race and socioeconomic factors.

For the study the research team led by Dr. Lumeng examined data from the National Institute of Child Health and Human Development, along with information on sleep patterns and other factors obtained from parents.

The survey included 785 children aged 9 to 12 who formed the basis of the study. Of the group 50% were male, 81% were white, and 18% were overweight in 6th grade.

The researchers found that children who were poor sleepers in 6th grade were more likely to be overweight in 6th grade.

They also found that shorter sleep duration in 3rd grade was also linked to overweight in 6th grade, independent of the child's weight status in 3rd grade.

They found that 6th grade children who were overweight slept less than children who were not overweight and most of the overweight 6th graders were boys.

Though boys reported sleeping fewer hours, girls reported more sleep problems, but sleep problems themselves were not associated with overweight.

The researchers say children between age 9 and 12 years who do not get 9 hours of sleep each night increase their risk of weight gain and the risk remained even after sex, race, socioeconomic status, or quality of their home environment was accounted for.

They suggest a preventive approach to overweight may be to ensure adequate sleep in childhood.

Dr. Lumeng says many children do not get enough sleep, and that lack of sleep may not only be making them moody or preventing them from being alert and ready to learn at school, it may also be leading to a higher risk of being overweight.

The researchers suggest insufficient sleep disrupts the hormones that control the storage of body fat, appetite and the metabolism of glucose. Lumeng says insufficient sleep changes the way the body uses carbohydrates, leading to changes in glucose tolerance, which can also affect weight. Hormones that help to control appetite and metabolism, are also affected and Dr. Lumeng says weight gain may not be a result of sleep's effect on behavior, but rather sleep's effect on hormone secretion in the body.

According to the National Sleep Foundation, preschoolers should get 11 to 13 hours sleep a night, elementary school children between 10 and 12 hours, pre-teens 9 to 11 hours, and teenagers should get 8.5 to 9 hours of sleep a night.

The study is found in the November issue of the journal Pediatrics.