Lightweight wrapping helps them wake up less frequently, cuts SIDS risk, study says

Babies who sleep in swaddling cloths wake up less frequently and get twice as much REM sleep during a nap as those sleeping with normal blankets, says new research. Moreover, swaddling babies appears to help them stay on their backs when they sleep, reducing the risk of sudden infant death syndrome, according to the study in the December issue of Pediatrics.

"Everybody's impression is that swaddles make babies feel safe and secure," says lead author Dr. Claudia Gerard, a clinical instructor in pediatrics at Washington University School of Medicine in St. Louis. "They slept really well. Quiet little babies sleeping."

In the study, Gerard and other researchers evaluated 26 infants during naps lasting an hour to an hour-and-a half. Each baby was laid to sleep with a conventional blanket, and then on a separate occasion in a tight swaddle made of cotton and spandex about the thickness of a T-shirt.

As the infants slept, the team measured their rapid eye movement (REM), breathing patterns, brain waves and the number of times they were startled or woke up. When swaddled, the babies not only woke up and startled less frequently, they also fell asleep again much sooner after arousal. And the length of REM sleep during the nap doubled for the swaddled infants, from about 450 seconds to 900.

"Now we have scientific evidence to support the age-old belief that swaddled infants sleep better than unswaddled infants," says Gerard, who is also a doctor at the St. Louis Children's Hospital.

The swaddle Gerard's team developed for the trial sculpted to the infant body shape. It allowed some movement, but restrained the infants enough to keep them on their backs. That technique, as well as the light weight of the swaddle fabric, corresponds with recommendations from other studies.

For example, in 1992, the American Academy of Pediatrics recommended that parents put toddlers to sleep on their backs, and as a result, the number of cases of sudden infant death syndrome (SIDS) has since dropped by 50 percent.

Moreover, a study just released in the Journal of the American Medical Association also supports the notion that babies should be wrapped in light fabrics. In that study, by the U.S. Department of Health and Human Services, researchers found that babies wearing at least two layers of clothing -- excluding a diaper -- had more than a sixfold increase risk of dying of SIDS.

"Over-bundling or over-clothing leads to overheating when the baby is sleeping," says Dr. Solomon Iyasu, an epidemiologist with the reproductive health program at the U.S. Centers for Disease Control and Prevention and lead researcher on the HHS study. "This relation has been shown in other studies as well."

Parents should ensure that clothing and blankets don't cover the face of their infant, which is also associated with SIDS. And when deciding how many blankets to put over an infant, parents should use themselves as a barometer, he says.

"It really depends on room temperature," Iyasu says. "We advise people to put as much clothing on the baby as would be comfortable for themselves."

In her research, Gerard has interviewed women from Eastern and Mideastern countries about how they swaddled their infants. Unlike Americans, who generally only wrap their babies tightly in the hospital, those women used a swaddle much longer.

"I think most people in America give it up once they get out of the newborn period. But other cultures in the world do it for six months, and in some cases 12 months," Gerard says.

The problem with the common American technique is that unswaddled babies can more easily flip onto their bellies when they sleep, which risks SIDS, especially during the infant's first six months, Gerard says.

Although she and her team now have a patent on the cotton/spandex swaddle they developed for the study, they don't intend to market it any time soon, she says.

What To Do

For recommendations about children's sleepwear, visit the American Academy of Pediatrics. For facts about sudden infant death syndrome (SIDS), visit the National SIDS Resource Center.