Our son just started flipping over onto his tummy at night. The first time, my husband found him on his face and quickly turned him over. We thought about trying a sleep positioner, but the product says once the baby can turn over himself it is not needed. He is able to raise his head now, but can he know to turn it to the side on his own? Also, we did not use a crib bumper at first and his legs got caught in the slats. We bought a mesh breathable bumper, which has been great. It is lower on the slats so his legs and arms can't get caught. Word to the wise,cloth bumpers cause possible suffocation due to CO2.