I have a Bedjet for this very reason. If you've never heard of it, it's basically a fan that pumps air from down on the floor where it's cooler up under the blankets or into a special comforter that blows up and circulates the air. In the winter, or whenever, it also has a heating function. You can set the temperature and it will continue to heat the air it blows to that temperature. Depending on the temperature you can run it for 12 hrs at a time, longer if you continue to add time, and it has different fan speeds. bedjet . com/
Yeah, major downside is that it cost so freaking much and unless you're able to save up or have come into some money, like your tax return, it's just hard to justify the cost. I would totally by it again but man it's really a shock to the wallet.
As well as running costs, I think it would be better to just buy a thinner blanket, or use a throw rug