Kids Who Skimp on Sleep Tend to Be Fatter

Kids Who Skimp on Sleep Tend to Be Fatter
MONDAY, Nov. 5 (HealthDay News) -- While the connection between achild's weight and the amount of sleep that child gets may not beimmediately apparent, new research has found a strong correlation betweenthe two.
Sixth-graders who averaged less than 8.5 hours of sleep a night had a23 percent rate of obesity, while their well-rested peers who averagedmore 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 beobese," said the study's lead author, Dr. Julie Lumeng, an assistantresearch scientist at the University of Michigan Center for Human Growthand Development.
Lumeng said that even after compensating for other factors, such as thehome environment, the link between less sleep and heavier weight was stillapparent.
The study results are published in the November issue of the journalPediatrics.
Lumeng said there are three likely reasons why sleep might affectweight. First, if children don't get enough sleep at night, they'll beless likely to run around and get exercise during the day. Second, whenkids are tired, they're more irritable and may reach for junk food to helpregulate their mood. And, finally, what Lumeng called a "hot area forfuture research" is the possible connection between sleep and fatmetabolism. She said there have been studies done with adults that haveshown that a lack of sleep may disrupt the secretion of hormones involvedin appetite and metabolism, such as leptin and insulin.
The new study included 785 children who were in third grade at thestart of the trial. Most were white -- 81 percent -- and half werefemale.
Parents were interviewed about their children's sleep habits when theyoungsters were in third grade and then again when they were in sixthgrade. The researchers also measured height and weight. Obesity wasdefined as having a body mass index (BMI, a ratio of weight to height)higher than the 95th percentile for age and gender, according to Lumeng.Eighteen percent of the children were obese in sixth grade.
The researchers also took into account maternal education, race, thequality of the home environment and parenting skills to see if thosefactors affected a child's weight.
No matter what a child weighed in third grade, too little sleepcorrelated with being obese in sixth grade. And, short sleep duration insixth grade also correlated with excess weight in sixth grade, accordingto the study.
Third-graders who got less than nine hours and 45 minutes of sleep anight had an obesity prevalence of about 20 percent, while those who gotmore than nine hours and 45 minutes of sleep had obesity rates of about 12percent, Lumeng said.
Those who were short-changing sleep in third grade had 40 percenthigher odds of being obese in sixth grade, and sixth-graders who weren'tgetting enough sleep were 20 percent more likely to be obese, compared totheir well-rested counterparts.
Lumeng said the researchers weren't able to find a statisticalassociation between quality of sleep and obesity. But, she said thatwithout a lab-based sleep study, it's difficult to objectively assess thequality of sleep, so there may be an association that this study wasn'table to uncover.
Dr. Stephen Sheldon, director of the Sleep Medicine Center atChildren's Memorial Hospital in Chicago, said he would've liked to seesleep studies so the researchers could have known more about the qualityof sleep these children were getting, such as how much REM sleep did theyget and how fragmented was the sleep?
But, he said, the bottom line is that "pediatricians and parents reallyneed to start paying closer attention to sleep-wake habits. In thissociety, we put a premium on being awake, and that premium may hurt us inthe long run. Sleep may be as important as food to our health andwell-being," said Sheldon, who's also a professor of pediatrics at theNorthwestern University Feinberg School of Medicine.
Both Lumeng and Sheldon recommended trying to keep a consistent sleepschedule. Bedtimes and wake times are both important -- for children andadults. Sheldon said it's usually OK to vary your sleep times a littlebit on the weekend, about an hour or so, but, he cautioned, "Letting youchild sleep till noon or mid-afternoon is inviting trouble."
Lumeng also recommended that children not have a TV in their bedroom,because it can make it more difficult to fall asleep.
More information
To read more about the connection between overweight and sleep, visitthe National Sleep Foundation.