Lack of sleep puts young children at risk of obesitySleeping more reduces body fat
Young children who don't get enough sleep are more likely to become obese, even after other lifestyle factors have been accounted for.
Previous studies had shown that there is a link between sleep and obesity in children, but this new study by scientists in New Zealand decided to investigate further.
They selected nearly 250 children who were taking part in a larger study (the Family Lifestyle, Activity, Movement and Eating study in Dunedin, New Zealand), and measured them once every six months between the ages of 3 and 7.
Details captured included weight, height, body mass index (BMI), and body composition. The children's physical activities were assessed by using a device called an accelerometer, a belt carrying a sensor that monitors body movement. Questionnaires at ages 3, 4 and 5 were used to determine the child's dietary intake.
In order to remove the effects of other factors with known links to BMI values, additional information such as birth weight, mothers' education, income, BMI, smoking during pregnancy and ethnicity was also captured.
The study found that children who sleep less have a "significantly" increased risk of having a higher BMI, even after the other factors have been accounted for.
Each additional regular hour of sleep per night during the years 3-5 resulted in a reduction in BMI of 0.49 and a 61% reduction in the risk of being overweight or obese at age 7.
This reduction in BMI was due to differences in fat mass, rather than any effect on fat-free mass, showing that fewer sleep hours has a direct effect on body composition.
This may be because reduced sleep could increase eating levels and affect energy use, leading to a reduction in exercise levels.
Commenting on these results, the authors of the study say that children should be encouraged to adopt good sleeping habits as a matter of public health policy.
The results are published online at bmj.com.
This article was published on Fri 27 May 2011
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