I have read that people in cold survival conditions have tried to stay awake, fearful that if they fall asleep they won't wake up. I have read others say that if a human goes to sleep then gets too cold, they will wake up on their own.

Where is the line here? It seems like if you are not yet hypothermic, going to sleep shouldn't be feared. You almost certainly need the rest. Perhaps though if you are already too cold and past the point of effective shivering then you may well not wake up.

Anyone have authoritative info?