| Something like an electric blanket, only it fits neatly around your mattress and heats from beneath you, which only makes sense considering that heat rises. It is one of three things that tend to make it very difficult to get out of bed on frosty mornings here in Michigan, the other two being flannel pajama bottoms and a snuggly bed partner.
Electric mattress covers are washable, available to fit various bed sizes, and sometimes come with dual controls. You can find them at JC Penney and probably other department stores. | 
