One of the kids got Wake Up, Dormouse, Santa Claus Is Here in their stocking one year. It is a little paperback and a good fit for the stocking. The author is Eleonore Schmid. I don't see much about her online.
from the back of the book:
Every winter sleep overcomes Gus, the dormouse, and he misses Santa CLaus's visit, but this year he is determined to stay awake.Amazon, which is where the picture above came from, doesn't have this book new.