I get night sweats all the time as well. My GI says that, in part, it's a sign that Crohn's is active, but it can also point to a specific infection that's going on. Usually, there's an internal fistula, abscess or some other infection that needs to be brought under control. When I'm having pretty bad night sweats, the GI usually puts me on antibiotics for 10 days (Cipro and Flagyl combo). InkyStinky's suggestion of taking your temperature and recording it is a really good idea.
On a 'coping' level, I make my bed with a fitted sheet, and I then put a large soft towel around the spot I usually sleep on. I then put another fitted sheet on top of that and then make my bed the way I always do. If I wake up at night and I've soaked my sheet, I take off the top fitted sheet, and then sleep on the fluffy towel for the rest of the night and the bottom fitted sheet doesn't get affected. Yeah, it's still a pain since there's still a lot of laundry to do, but at least I don't have to change my sheets in the middle of the night (the first time I had to do it, I stepped on the dog on the way to find my sheets, and it was a lot of mayhem at 3am!). I also keep another towel close by to wipe off my body/hair during the night.
I would definitely echo others' suggestions to call your doctor.
Good luck, Joni O.