Jenna sleeps up on a pillow in our bed so shes not under the covers, but its not her head, its sort of her whole body on it if that makes sense?
I actually gave her a pillow last night, shes a bit snuffly, and having her head on a pillow seems to make her breathe easier. It came out this morning though and she had a good day sleep.
I think I'll wait a little longer before giving her one full time now - but on occasion when she is having trouble sleeping it seems to help. I too like Lucy's idea