Yes, Boo sleeps nearly all night under the covers. My DH and I like a cold room to sleep in, but I like lots of blankets too. So in the summer time while my DH only needs the sheet and one blanket, I have that blanket plus 2 others fold in half, so basically 5 blankets.
Yes, I know, weird, but I just love how comfy it is to snuggle under all those blankets. Boo will sleep on my side of the bed, under all those blankets too. I have always wondered how he breaths down there, but he does just fine. He'll come out every now and then shake to fluff up his fur and crawl right back under.