Forgotten Christmas movie title

I need help identifying a movie. I don't have much hope since all my searches never turned up anything even remotely close, but maybe I'll get lucky here.

I watched this movie as a young kid, so I don't really remember a whole lot about it.

What I do remember:

It was Christmas-based.

Lead character was a little girl with long blonde hair. She was in her nightgown for the majority of the movie, so I'm guessing that it takes place during the span of a single magical night.

Other characters were loveable monsters that came out of the little girl's closet from their own world which was somewhere "wintry".

My memory leads me to believe that the girl had to somehow save the monsters or their world or something . . . take that much with a very large grain of salt.

Main theme seemed to be the Christmas song, "Silent Night". I remember the melody being played a lot, or at least something similar to it. This is what I thought the movie was called, but a search yielded no results.

This movie was probably made during the 80s since this is when I probably watched it, but it also could've been made in the late 70s.

So there you go, all that I remember. I don't expect much, but if you have any clues, please share. It would be greatly appreciated.

Thanks!