Kids Who Skimp on Sleep Tend to Be Fatter

By Serena Gordon
HealthDay Reporter
Tuesday, November 6, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

MONDAY, Nov. 5 (HealthDay News) -- While the connection between a child's weight and the amount of sleep that child gets may not be immediately apparent, new research has found a strong correlation between the two.

Sixth-graders who averaged less than 8.5 hours of sleep a night had a 23 percent rate of obesity, while their well-rested peers who averaged more than 9.25 hours of sleep had an obesity rate of just 12 percent, according to a new study.

"We found that children who got less sleep were more likely to be obese," said the study's lead author, Dr. Julie Lumeng, an assistant research scientist at the University of Michigan Center for Human Growth and Development.

Lumeng said that even after compensating for other factors, such as the home environment, the link between less sleep and heavier weight was still apparent.

The study results are published in the November issue of the journal Pediatrics.

Lumeng said there are three likely reasons why sleep might affect weight. First, if children don't get enough sleep at night, they'll be less likely to run around and get exercise during the day. Second, when kids are tired, they're more irritable and may reach for junk food to help regulate their mood. And, finally, what Lumeng called a "hot area for future research" is the possible connection between sleep and fat metabolism. She said there have been studies done with adults that have shown that a lack of sleep may disrupt the secretion of hormones involved in appetite and metabolism, such as leptin and insulin.

The new study included 785 children who were in third grade at the start of the trial. Most were white -- 81 percent -- and half were female.

Parents were interviewed about their children's sleep habits when the youngsters were in third grade and then again when they were in sixth grade. The researchers also measured height and weight. Obesity was defined as having a body mass index (BMI, a ratio of weight to height) higher than the 5th percentile for age and gender, according to Lumeng. Eighteen percent of the children were obese in sixth grade.