I lived in a place one time which had a cement floor in the bedroom. (No kidding, hold my beer, woman.) One night as I was laying on the bed, watching TV, noticed my one foot was less cold than the other. Some investigation finds two layers of carpet under one foot, one lay under other foot. I moved the carpet scrap to be under both feet, and that was much more comfortable.
Since that time, I've moved. However, I've made sure to always have a carpet sample next to the bed where my feet land.
Some carpet stores sell samples of old design carpet. Those can make great foot pads.