Previously, the AAP said that babies should sleep on a separate surface, in the same room, at least until six months and preferably until 1 year old to decrease the risk of Sudden Infant Death Syndrome (SIDS), from which the CDC says 3,500 infants die each year.

Now, a study of mothers and infants from Pennsylvania State University finds that room-sharing may have unintended consequences and recommended a change in the long-held AAP infant sleep guidelines.

For the study, researchers looked at 256 parent-infant pairs through age 9 months. They divided the pairs who participated in the study into two groups: one that received only education on preventing SIDS and one that received both SIDS education and encouragement for the parent to have the child sleep in a separate room by 4 months of age.

At 9 months old, infants in the study who had slept on their own by 4 months of age had longer stretches of uninterrupted sleep, averaging 46 minutes more, compared to infants who shared rooms with parents. These earlier independent sleepers also slept about 40 minutes longer, on average, at 9 months of age.

And the researchers found another trend: Parents who kept their babies in the same room to sleep were much more likely to bring their infants into their adult beds in the middle of the night -– a practice that the AAP says is dangerous for babies.

The authors noted that the discrepancies in sleep could have been caused by additional factors, as well. For one, parents whose babies did not sleep as well may have preferred to keep their infants closer at night and not all families had the ability to have separate rooms for their babies. Different cultures may also have preferences for either same-room or independent sleep and some independent sleepers may have woken in the night and soothed themselves back to sleep without parents knowing.

They recommended removing the guideline for parents to share rooms with their infants at night through age 1 until further evidence supporting its benefits could be found.