I used to spend some time in my younger days wondering why we don't have a tent-like cavity in/on our beds into which we can insert ourselves and be toasty, sans nightclothes and with no covers touching, maybe with a kayak-like skirting around one's neck... You suppose it could work?

On a documentary I watched recently a journalist in Siberia was given a 'bed' that was like a hairy womb. The outer shell was a tent apparently made of gut or some other translucent material. Inside it was a small tent that was lined with reindeer hides, hair side in. On the 'floor' were piled more hides. There were a couple of fat candles that warmed the air but he was given no covers. He stretched out- and reported in the morning that he had been toasty.