MADELEINE BRAND, host:
In these crazy days leading up to the holidays, it seems like no one gets enough sleep and everyone wishes they could drop a few pounds, or at least not gain any.
For adults, at least, it's been shown that sleep deprivation and obesity are linked. The less we sleep, the more we weigh. But is that true for children?
Our medical expert Dr. Sydney Spiesel is here. He's a practicing pediatrician and also a professor at the Yale Medical School. And welcome back to DAY TO DAY, Syd.
Dr. SYDNEY SPIESEL (Yale Medical School): Hi, Madeleine.
BRAND: Well, I understand there's a big study out now on children's weight and sleep patterns, right?
Dr. SPIESEL: Oh, yes. It's actually kind of an interesting study. They took a thousand kids who were from a very wide range of - I think 10 areas around the country. And one of the things they were looking at is what are the things going on at home: parenting, demographics, behavior problems, whether there's chaos at home, the kids are getting adequate attention, and patterns like sleep. And then these kids were checked for height and weight at third grade and sixth grade.
BRAND: And they found a link?
Dr. SPIESEL: Oh, they did. What they found was that if the sleep duration of the children were shorter, it led to an increased risk of obesity. It was actually pretty marked. If they just looked at the sixth grade kids, the kids who got on average one extra hour of sleep at a 20 percent lower chance of being obese. If they went back to the third grade, and here it didn't even matter whether the kids were obese or not, if they got one extra hour of sleep and then they looked at those same kids three years later in sixth grade, they had a 40 percent chance - less chance - of being obese.
BRAND: So can we then conclude that a lack of sleep causes children to be overweight?
Dr. SPIESEL: Well, we'd love to be able to conclude that, but you really can't. We just don't know enough yet. We can just see there's an association, but what causes what or perhaps the same factor causes both things. So perhaps, for example, irritable kids because of a lack of sleep are fed more to pacify them. Maybe hungry kids sleep less or there's a hormone that regulates appetite, which is released in sleep and maybe less of that hormone is released. Really, it's very hard to make a causal connection, but there really does seem to be an association.
BRAND: And is it the same with adults, the same kinds of hypotheses?
Dr. SPIESEL: Yeah. It's the same kinds of hypotheses. Some have been kind of ruled out in adults. For example, you might think that because people are sleeping more they have less time to be active and so they spend more time eating. And it turns out that they are less active but the activity level doesn't regulate obesity at all in that way. It's separate from the sleep.
BRAND: In terms of being healthy and not gaining weight, what is the ideal amount of hours of sleep per night a child should be getting?
Dr. SPIESEL: Well, it depends on age, of course. Younger kids need more sleep. Older kids need less sleep. For kids in the sort of third grade to sixth grade range, we think about for most of those kids about nine hours seems reasonable. But every kid is a little bit different. We have to take that into account also.
BRAND: Well, thank you, Syd.
Dr. SPIESEL: Thank you.
BRAND: That is opinion from Dr. Sydney Spiesel. He's a pediatrician and also a medical professor at Yale. You can read his Medical Examiner column at Slate.com.