By Alok Jha
Scientists have found that getting a good night's sleep reduces a child's chances of being obese.
Every additional hour of sleep a night a child gets at the age of eight or nine reduces the risk of obesity at the age of 11 or 12 by 40%.
Julie Lumeng of the University of Michigan, who led the research, said that getting more than nine hours 45 minutes of sleep lowered the chances of obesity in later life significantly.
"Many children aren't getting 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," said Dr Lumeng. The study appears in this month's issue of the journal, Pediatrics.
Though scientists are not certain how sleep would directly affect a child's weight, Dr Lumeng said well-rested children may be more energetic and more likely to go out and play, rather than lying around watching TV. Tired children may seek out food when they become irritable or moody, she added.
According to Eve Van Cauter, an endocrinologist at the University of Chicago who was not involved in the new research, lack of sleep can disrupt the production of two hormones involved in regulating appetite.
Her own experiments show that sleep-deprived adults produced more ghrelin, a hormone that promotes hunger, and less leptin, a hormone that signals fullness.
Dr Lumeng's team analysed details of sleep, height and weight of 785 children when they were eight and again when they were 11. The children came from 10 US cities and were part of a larger federal study. On average, the eight-year-olds got about nine-and-a-half hours' sleep but some slept as little as seven hours and others as much as 12.
Of the children that slept 10-12 hours a night, 12% were obese by the time they were 11. Of those that slept less than nine hours at eight, 22% were obese a few years later. The research team controlled their experiment for other obesity risk factors, such as the children's body mass index when younger, but acknowledged that the parents' weight and behaviour - which may also have an influence on a child's weight - had not been taken into account.
Jodi Mindell ,of the Children's Hospital of Philadelphia's sleep centre , said there were many reasons for encouraging good sleep habits, such as success in school. "I don't want parents to think, 'If I get her to sleep, she's not going to be overweight'. I think this is a small piece in the picture."
Dr Lumeng's study concluded: "Our findings also provide additional support for policies that propose later school start-times. The very early school start-times for US adolescents have raised concerns in the paediatric community because of their apparent adverse impact on sleep duration and, consequently, children's general academic and behavioural functioning."
No comments:
Post a Comment