This is the issue: in the evening, my body temperature drops down a bit, so I tend to be cool-but-not-cold when I'm getting ready for bed. Then I climb into my cold bed, and suddenly, I'm shivering and cold until I manage to produce enough heat to warm up my mattress enough to let me warm myself up enough to finally fall asleep. This is suboptimal.
I've considered putting an electric blanket under my bottom sheet and turning it on for a few minutes before I get into bed. Does anyone else have any bright ideas?