What Causes Tingling And Numbness In Fingers?

hello, for the past month I wake up in the middle of the night with my left are tingling and hurting, fingers are almost numb. So I start to make a fist and close it for several times after a while it goes away. I'm very concerned about this, I'm a 48 year old female with no family history of heart attackes or strokes. how ever I have recently gained some weight, but it's not cause I sleep on the arm.