Blankets and more blankets

During winter my son is always looking for some more blankets to put on his bed. He is always cold so his bad is always stuffed with warm clothes.

This Winter I was thinking about buying him a heated blanket but I must confess I am afraid of this type of blankets. If they are connected to the electricity isn't it possible that we can get an electrical shock? I'm sure we won't but I'm still afraid.

I really want to see this option and others because an heated blanket or an heated mattress would be a great solution for cold nights.