Cold vs. Sleep
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Climbing into a freezing cold bed is no fun. And electric blankets creep me out, but I'd still like to be warm at night. I've found that if I put a hot water bottle in the foot of the bed my nighttime experience is a lot less like jumping in a lake. People have done this throughout history with a hot rock or a pot of coals, which I'm sure still works if someone is down for trying that.