snuggle down (into something)
To settle or nestle down (into something) snugly and comfortably. I held my favorite teddy bear close to my chest, snuggled down into my bed, and fell fast asleep. She snuggled down and spent the rest of the afternoon watching reruns of her favorite TV show.
snuggle down (with something)
to nestle [into something] with something, such as a blanket, doll, book, etc. The baby snuggled down with her blanket and was asleep in no time. Sally grabbed onto her favorite doll and snuggled down for the night.
snuggle down
(with someone) to nestle [into something] with someone else. Billy snuggled down with his sister in the big feather bed. They snuggled down and went to sleep.