Moose gets the leg/calf cramps in bed too.
Hate 'em! Usually come on when I stretch my legs with toes pointed. Have to grab my cane to pull my foot back up to an 'L' shape.
Lady Express gave good advice. One thing I can add is that if you're out and about sweating a lot, the lack of salt/sodium/potassium in you can bring them on. My Dad gets them prety bad too.
Hope you find a fix for it soon.