If I’m really warm in my bed and I have to get up to go to the bathroom and the house is cold, occasionally I will start shivering and almost shaking uncontrollably with my teeth chattering. I have to immediately get under blankets or heat up a heating pad or get in the shower to warm up. Has this ever happened to you? Is it normal? It only happens to me when I’m really warm and toasty and then suddenly go outside where it’s freezing or when I get out of bed.