Hi Im A 49yr Old Female, I Took A Nap

Hi Im a 49yr old female, I took a nap today and when I woke up I was shivering I was so cold it took about ten minutes of moving around with a hot cup of coffee to stop shivering. This is not the first time this has happened. I'm not running a fever and am not sick. I have woke up cold in the middle of the night but that was because of night sweats and my clothes were wet. There was no sweat today. Any ideas?