After these new socks arrived, I waited until my feet felt chilled in bed. I put these socks on and got back in bed. My feet are amazingly warm! The fluffy fleece on the inside really works. The socks are true to size and are not too tight for comfort during sleep. They give me a light zone of warmth all around my feet and ankles. The only thing I don't love is that one of the two socks has an inch-long, rectangular Heat Holders logo patch fused onto the outside of the sock, at the ankle, like an iron-on patch. The manufacturer needs to get rid of that patch. But I am very satisfied with these socks and glad I got them.