Swaddling an infant may sound like something from Biblical times, but researchers say the method helps infants sleep better and keeps them on their backs -- which reduces the risk of sudden infant death syndrome.

The findings from researchers at Washington University School of Medicine in St. Louis are published in the December issue of the journal Pediatrics.

SIDS deaths have decreased nearly 50 percent since the American Academy of Pediatrics recommended in 1992 that babies be placed on their backs to sleep, according to the article. But when infants reach 2 months of age, about 20 percent of parents in the United States place their babies on their stomachs to sleep because they say they appear more comfortable or to sleep better.

"That's also the time when babies have enough strength and are big enough that they can escape from the typical 'burrito' wrap style of swaddling," said Dr. Claudia Gerard, a clinical instructor in pediatrics and lead researcher in the study. "But in other cultures where swaddling is practiced, it's common to continue swaddling babies until they are much older."

Swaddling is practiced almost universally in newborn hospital nurseries, and various traditional swaddling techniques are practiced in Turkey, Afghanistan and Albania, according to Dr. Bradley Thach, a professor of pediatrics.

Swaddling may make a baby feel more secure and may limit the startle reflex, which wakes babies during their sleep. If infants sleep more peacefully on their backs while swaddled, parents would be less likely to intervene and change infants to the risky stomach-sleeping position, Thach said.

Researchers studied the effect of swaddling on 26 infants 3 weeks to 6 months old. The infants were either wrapped in a specially designed cotton spandex swaddle, or not swaddled at all during daytime naps. The cotton spandex swaddle did not restrict the babies' hip movement or breathing, but it did limit their breaking free of the swaddle.

The researchers found that the duration of REM sleep was nearly doubled in babies who were swaddled than in those who were not.

"Now we have scientific evidence to support the age-old belief that swaddled infants sleep better than unswaddled infants," Gerard said. "It helps babies stay asleep and so may help parents keep their babies sleeping in the safer back position."