I'm hot natured and sleep under a sheet only, No blankets. I also use CPAP with a nasal mask while breathing air at room temp only with no heat or water. I keep the temperature at around 66 degrees F while sleeping and have experienced what I believe is hypothermia 3 times now with the last incident being worst by far. I woke up shaking extremely cold and foggy minded. I drove to work in what seemed like a dream. I kept running off the road shoulder but made it there. I opened the door stepped out and melted to the ground. Next thing I'm in the hospital for 8 days while they tried to figure out what happened to me. I told them that it was hypothemia but they didn't believe it. MRI, Brain scan, blood work all was normal except that now I have Atrial Fibrillation. I believe what sleeptech said above is correct but I also know what happened to me.
I think I know why it happened. I seem to always move my mask around until i get a small amount of leakage. I can breath easier when there is a little moving air it seems. I believe that this leakage, i.e. the moving air, causing evaporation in my nasal passages further reduces the air temperature I take in. After enough time my body core temp drops to the point of hypothermia. It's a combo of things, low metabolism, cold house, evaporation cooling due to leaking mask, a sheet as the only cover. etc.
Needless to say I have taken steps to prevent this from happening again. It was so scary.
