I am in the same boat and along with the dry mouth, I had was extremely congested, almost like a severe chest cold. Using a nasal mask, I wake up two or three times in the middle of the night and my mouth and throat feels like I was French kissing the Sahara desert. I had to have a bottle of water next to my bed to relieve this. Tried a number of things including a chin strap. That worked, but it was extremely uncomfortable wearing it. I used a full face mask which solved all the problems except for the fact that the full face mask I was rolled into is a real P.O.S. but that's another story.
Good luck, hang in there.
To Error is Human but to REALLY screw things up
YOU NEED A COMPUTER!
The beatings will continue until morale improves!