I also suffer from this and can find no reason. I am type 2 have spoken to the Dr about it kept a diary etc. nothing leaps out as causing it.
I do get test strips etc. because I have to take insulin, and I have tested when the sweats wake me during the night and have been high, low and normal with perhaps slightly more on the high side. So was told not to eat before bedtime, don't normally anyway.
Finally told to lose weight and see if that helps, easier said than done when you have an underactive thyroid and they keep changing medication. Have been trying though and have managed to lose a stone in 6 months.
I also get high doses of steroids and wondered if it was that, but no didn't match up .
My best advice is go to your Dr you may find you have an obvious reason when you talk it over with them.
Sorry not very helpful but you are not alone.