I am going to throw this recent experience that I had into the conversation(recent as a few hours ago)
I drove to a wooded gated community that I had been to several times before, and on my way out, I got "lost" amongst the few roads that encircled a fairly small area. I called a friend of mine and told him that I could not find my way out of this #$%&^*!! little revine. I was having trouble thinking straight. Finally, my buddy asked me when was the last time I ate? Oh, yeah....yesterday at 5:00pm (It was now 1:00pm the next day) Deprived of food, I could not even make simple decisions about how to exit a small community with limited choices.
I can only imagine what it would be like to add fatigue, cold, darkness, AMS etc to the mix.
I eventually made a complete loop of the community and by default, found the exit.
