When someone reacts SO far from normal, some underlying condition is probable. I am glad he and his doctor figured that out. I am very cold-blooded myself. I really have trouble generating heat once I stop moving. I do not have much excess fat for insulation! For me, it is critical that when I enter my sleeping bag, I am really warm. I usually take a brisk walk right before bed. I am the coldest at first and it may take two hours before I finally get all the air space warmed inside the bag. It does not matter if it is 45 degrees of 20 degrees- I am cold until I get the bag warmed up. I also start out with a balaclava on my head- otherwise I get the cold neck syndrom. My husband does well in a blanket; I would never consider it- need my sleeping bag with hood and draft collar! The big jacket may have contributed to coldness. It both over-warmed his core (causing sweat) and failed to allow his body heat to warm the space under the blanket too.