B.T.
My son was a light sleeper as a baby and just rolling around on the pack-n-play mattress was too noisy for him! I put a polar fleece and/or flannel blanket on the mattress and then covered with the pack-n-play sheet so it was tucked in and not possible for him to get rolled up in the blankets. It helped and the mattress was not so "crunchy" sounding then! If you're worried about it being too warm with the polar fleece, a towel should work fine too. Good luck!