Study Links Lack of Sleep to Weight Gain in Babies Infants and toddlers who slept less than 12 hours a night were more than twice as likely to be overweight by age 3. That's according to a study in this week's Archives of Pediatrics and Adolescent Medicine. Other studies have produced similar findings with school-age children and adolescents.

Study Links Lack of Sleep to Weight Gain in Babies

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STEVE INSKEEP, host:

Here's something to keep in mind as you struggle out of bed. There is more evidence that how much you sleep affects how much you weigh, even if you're as young as 3 years old.

NPR's Patti Neighmond reports.

PATTI NEIGHMOND: Researchers from Harvard University interviewed moms and weighed 915 babies, beginning at birth and then again at 6 months old and at 3 years old.

Pediatrician Elsie Taveras headed the study.

Dr. ELSIE TAVERAS (Pediatrician): Infants and toddlers who slept less than 12 hours a day were twice as likely to become overweight at age 3 than children who slept longer than that.

NEIGHMOND: And longer meant about 13 to 14 hours of sleep a day. Less than 12 hours a day meant they were twice as likely to become overweight. Now, other studies have produced similar findings with school-age children and adolescents. They found the longer they slept, the less likely they were to be overweight. That might seem counterintuitive, and Taveras agrees.

Dr. TAVERAS: When we started looking into this relationship, we actually thought the same thing you just mentioned. We thought it would be the opposite, right? That children who slept more weren't as physically active, and maybe that would be one way in which they would be overweight.

NEIGHMOND: But instead, Taveras says, it seems that a healthy night's sleep produced the right amount of appetite hormones. That's evident, she says, from research done with adults.

Dr. TAVERAS: They've brought these adults into lab settings, and they restrict their sleep or they interrupt their sleep. And they have found that their appetite hormones are completely out of whack.

NEIGHMOND: Stanford University psychiatrist Emmanuel Mignot did the study she's talking about. Mignot specializes in sleep disorders, and in the study, he looked at 1,000 healthy adults who normally slept about eight hours a day. They were brought into a sleep lab and had their sleep disturbed, so they ended up sleeping only five hours a day. Every morning, their blood was taken and hormones measured.

Mignot.

Dr. EMMANUEL MIGNOT (Psychiatrist, Stanford University): So somehow, the brain sends signals to the fat cells and to the stomach to change the production of these hormones that regulate appetite to tell them, eat, eat. And that's why probably sleep deprivation stimulates hunger, and that's why people eat more, and that's maybe why when you sleep too little, you have a tendency to gain weight.

NEIGHMOND: Which Mignot says is probably the reason why people eat more when they sleep less. Hormones tell them to. That, plus the obvious: If you're sleeping, you're not eating. And speaking in terms of human evolution, Mignot says this makes a lot of sense.

Dr. MIGNOT: In the past, wakefulness - I mean, how much you are awake - was devoted to searching for food, and you were burning a lot of calories to get food. You had to run around and hit a rhino with a - you know, with something. I don't know. And then you get the food. So it took some effort whereas now, it's just opening the fridge.

NEIGHMOND: Who knows how many calories it took to hunt a rhino. We'll probably never know. But Mignot says whatever it was, our human ancestors probably experienced a healthy correlation between activity and food consumption. Today, temptation abounds, and there's no amount of exercise that can compensate for a daily diet of, say, fast food and snacks.

Other studies in the same issue point to more healthful benefits of sleep, including fewer emotional, mental and physical health problems later in life.

Patti Neighmond, NPR News.

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