Hospital blankets must be made from lead, but I don't know where they get them. Quilts are usually pretty dense.
I have this argument with my wife: in the winter we have a very nice down comforter. It is plenty warm on its own. She likes to through a heavy quilt we have on top of that. I say that it makes the bed colder... the quilt compresses the down in the comforter and it loses much of its insulation ability that way, more than the insulation added by the quilt on top. She refuses to accept this argument and says it's warmer with the comforter plus the quilt. I haven't wanted to win the argument badly enough to start taking measurements, but as a compromise, we've worked out having her double up the quilt on her side.
A long time ago they may have been made out of thick wool. I don't know if you've ever heard of or slept under a "military blanket" of the wool variety, but they're incredibly heavy and warm for their relative thickness.
I have this argument with my wife: in the winter we have a very nice down comforter. It is plenty warm on its own. She likes to through a heavy quilt we have on top of that. I say that it makes the bed colder... the quilt compresses the down in the comforter and it loses much of its insulation ability that way, more than the insulation added by the quilt on top. She refuses to accept this argument and says it's warmer with the comforter plus the quilt. I haven't wanted to win the argument badly enough to start taking measurements, but as a compromise, we've worked out having her double up the quilt on her side.