Eat banana before you go to bed should help
Keep a bottle of mustard and a spoon next to your bed, (as weird and gross as it might sound) mustard instantly takes the cramping sensation away.
I started getting leg cramps around that time too! Charlie horses! Hurts like crap! And they would come out of nowhere in the middle of the night and wake me up immediately! Try what Sarah said....bananas and plenty of water and maybe try to get some leg rubs in if you can!
Maybe try eating a banana before you go to bed. When I was getting cramps that helped me. And make you you are drinking plenty of water.