Placing your baby on their back to sleep is one of the most powerful things you can do to protect them. Research suggests this single change has cut sudden infant death syndrome (SIDS) risk roughly in half over the past 20 years. Back sleeping works for naps and nighttime sleep. Your baby might seem like they're in a vulnerable position, but studies show this is actually when they're safest. If your baby naturally rolls onto their side or stomach after you've placed them on their back, you don't need to reposition them—just always start with back sleeping. This simple practice is one of your best defenses.