May 27, 2011

Heavier Children Sleep Less

Children who are overweight may not be getting enough sleep at night, according to researchers in New Zealand.

Their study, published in the online edition of British Medical Journal, followed 244 children between the ages of three and seven. The results showed that more sleep was linked to a lower weight, which could have important public health consequences, The Telegraph reports.

UK experts said there was "no harm" in drawing attention to the link between reduced sleep and ill health. The children were seen every six months when their weight, height and body fat were measured. Their sleeping habits and physical-activity levels were recorded at ages three, four and five.

The researchers discovered that children who had less sleep in their earlier years were at greater risk of having a higher Body Mass Index by age seven.

Not getting enough sleep affects levels of two hormones - leptin and ghrelin - that are involved in appetite control. Sleep deprivation decreases levels of leptin, and increases levels of ghrelin. Low levels of leptin tell the brain to eat more, while high levels of ghrelin do the same.

"Youngsters who sleep less are more likely to be overweight, with high body fat values, even after adjustment for lifestyle variables," the study claims. Researchers recommend, "Appropriate sleep habits should be encouraged in all children as an appropriate public health measure."

Suggested reasons for the link include simply having more time to eat and changes to hormones affecting appetite.

Dr. Ian Maconochie, from the Royal College of Pediatrics and Child Health explains, "Children under five generally average at least 11 hours sleep at night and in daytime naps. However, 20% of children at this age experience problems sleeping, and we already know that inadequate sleep has a significant impact on attention, memory, behavior, and school performance. This paper is a useful addition to our knowledge of children's sleep patterns."


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