I quite often wake up at night after a few hours' sleep because I'm too cold (especially at the moment). The solution doesn't seem to be to pile on more blankets because I'd be too hot to start with. I'd rather go to sleep and stay a comfortable temperature all night and not wake up at all until the morning. But how to manage it? I saw that @Ryan31337 is planning a thermostat-controlled heated bedsheet (?) but that kind of thing is technologically way beyond me and I don't like the idea of Bed + electricity = fire risk. Is there some kind of secret of comfortable sleep that I don't know?