Why do i feel like my legs want to cramp a lot at night. sometimes they do, but most of the time they just feel heavy and seem to be on the edge of it?

Bad circulation: Although your symptoms are a little vague, you may have poor circulation in your legs causing those cramps feelings. Venous congestion from varicose veins and poor flow can cause crampy discomfort but arterial insufficiency from peripheral vascular disease can be more serious. Maybe your just sleeping in the wrong position. Either way you need to be evaluated by a physician.