My son suffered from GERD and until he knows to turn one's back on the belly I was very anxious to the idea of sunset in a single sleeping bag! This baby has bilge nights save our son and ours too! We knew our son safe on the back, without opportunities to turn in the night. He always slept on his back and never had a flat head worries! However its use with a sleeping bag is not really suitable (with the pants) ...