Combating high childhood obesity rates is a vexing problem: Diets and other interventions often don’t work, and when they do the effects aren’t long-lasting.
Now, some researchers are attacking the problem at the newborn stage with an unlikely target: sleep.
Newborns whose parents received advice and hands-on education about sleep had about half the risk of developing obesity by ages 3½ and 5, compared with children whose parents didn’t get the sleep instruction, according to a study published in the American Journal of Clinical Nutrition in August.
“It really does look quite promising in this context, and it should be investigated further because it was a very brief intervention and it has these really quite incredible long-term effects,” says Rachael W. Taylor, director of the Edgar Diabetes and Obesity Research Centre at the University of Otago, New Zealand, and first author on the study.
The findings are similar to those in a Pennsylvania study published in JAMA medical journal in August, which focused on education for new parents that included sleep as one component.
In the New Zealand study, the researchers recruited about 800 women in the later stages of pregnancy and divided them into four groups. In one group, expectant parents attended education sessions on strategies to help babies fall asleep on their own. Nurses made home visits three weeks after the babies were born. “They were really trying to promote getting the babies to learn to settle themselves to sleep,” says Dr. Taylor. “This was very much to prevent sleep problems from developing in the first place.”
The families were offered more help at 6 months of age but only about a quarter said they needed it.
For a second group, nurses educated parents on nutrition and physical activity—but not sleep—before the babies were born and until they were 18 months old.
A third group of parents got education on both sleep and nutrition. A fourth group was the control group and received only government health visits that are standard in New Zealand.
By the ages of 2 and 3½, the babies whose parents had the sleep instruction either alone or in combination with nutrition education had half the risk of obesity as the other groups. By age 5, the effect was slightly stronger.
One unexplained surprise: The children of parents who received instruction on nutrition had higher obesity rates by age 5 than the control group. That could mean there is no benefit to additional nutritional counseling when some of that is covered in standard care, Dr. Taylor says.
Another surprise: the researchers didn’t see a change in sleep duration between the four groups, so they aren’t sure what to attribute the lower obesity rates to. “The main evidence in the observational literature linking sleep and obesity is sleep duration,” Dr. Taylor says. But sleep duration is difficult to measure accurately in young children, she notes. For this study, the researchers had babies wear accelerometers to detect motion and also used questionnaires for the parents.
The questionnaires showed the parents who received the instruction on sleep used more positive parenting strategies, such as smiling and praise, which Dr. Taylor speculates could play a part in lowering the babies’ obesity rates. Such findings were published in May in the journal Child Care in Practice.
One limitation of the New Zealand study: About a third of parents did not complete the five-year assessment.
Its findings are similar to those in the recent JAMA study. In that trial, about half of 279 first-time mothers in Pennsylvania received home visits from nurses four times over the course of a year for education on babies’ feeding, sleep, play and emotional regulation.
The other half were randomly assigned to a control group that had the same number of nurse visits, but focusing on safety.
The researchers looked at the rate of overweight and obese babies at 1, 2 and 3 years of age. The babies in the control group, with only safety instruction, had more-rapid weight gain, a strong predictor of later obesity, says Jennifer Savage, a co-author on the study and director of the Center for Childhood Obesity Research at Penn State University.
Unlike the New Zealand study, in the Pennsylvania study the researchers found that the babies’ sleep duration did increase in the other group, and they had a shorter bedtime routine.
“The whole premise was trying to teach parents responsive parenting skills and have them practice those with the hypothesis being that by being more responsive a child is able to learn to self-regulate,” Dr. Savage says.
Evidence is mounting that sleep could be an effective weapon in fighting obesity, says Jodi A. Mindell, a psychology professor at Saint Joseph’s University in Philadelphia who specializes in children’s sleep.
“This does not mean that you start doing sleep training at two weeks of age,” says Dr. Mindell, who wasn’t involved with the New Zealand study but was a consultant on the Pennsylvania trial. She advises that when babies are 3- to 6-months-old, parents should start instituting bedtime routines, early bedtimes and strategies aimed at getting babies to sleep at bedtime and go back to sleep when they wake up.
While it’s unclear how better sleep leads to lower obesity rates, Dr. Mindell says one theory is that if a baby is waking less throughout the night he or she may be consuming fewer calories in nighttime nursing or bottles. Another potential mechanism is that less disruptive sleep may affect metabolism in the short- and long-term.
The research groups at Penn State and in New Zealand have created a consortium to discuss future studies. “We’re trying to narrow it down to see what are the smallest things that you can do as an intervention—which aspects of sleep interventions are leading to these outcomes,” Dr. Mindell says.
Write to Sumathi Reddy at firstname.lastname@example.org