What Causes Numbness And Discolouration Of Feet And Hands?

I have been having issues in my feet/toes and hands/fingers. While sitting upright in a chair or laying on the couch, my extremities turn purplish/blue. It has always kind of happened, but in the last 3 months, it s has been worse. Sometimes it goes numb, if they discolor enough. Seems like a hot bath or my electric blanket will fix it temporarily.