In the study, published February 3, 2010, in the Journal of the American Medical Association, researchers from Harvard University found that babies who die from SIDS appear to have abnormally low levels of serotonin, a brain neurotransmitter that—among its many functions—helps to regulate breathing, heart rate, and blood pressure during sleep.
According to researchers, SIDS may occur when babies with low serotonin levels are placed face-down to sleep during their first year of life and are unable to regulate and stabilize their breathing in this position. (Sleeping face-down decreases the amount of available oxygen and increases CO2 levels; bedding or blankets are also more prone to block the nose or mouth when baby is face-down.) Researchers hope these findings someday lead to infant serotonin testing as a way to identify newborns at greatest risk for SIDS.
Though researchers have long known that placing infants to sleep on their backs appears to significantly reduce the risk for SIDS, why a back-lying position was so effective remained elusive.
Are you doing your part in putting baby "back to sleep"? Create a safe sleep environment by only putting baby on his back to sleep in a safety-approved crib with a snugly fitting, firm mattress. Bedding—such as a well-fitted sheet—should also be firm underneath your infant. Soft bedding, pillows, blankets, quilts, comforters, wedges, sheepskins, and stuffed animals may cause a dangerous buildup of carbon dioxide around a child's face, increasing the risk of SIDS.
Also be sure to keep your baby's environment smoke-free and don't allow your infant to get overheated with excessive bedding, clothing, or a room heater. And because you are not always the adult who puts baby to sleep, educate grandparents and other caregivers about why sleep position is so important.