My daughter sleeps under our cover, but properly. See, I sleep lower on the bed so that the blanket can go up to my neck, and put her up higher so that the blanket does not come above her armpit. I also tuck it under her, so that she doesn't accidentally pull it up when she's fussy right before falling asleep. In addition, I am VERY aware of the situation, even though I am asleep. So yes, we use the covers, but take precautions. Summer time really is so much easier, with just a simple cotton sheet!!