Just a quick follow up to the last post. There's a new thread on AvCanada about Flying Exhausted. They've included a poll the results of which as of March 18th, 2008 @ 7:28pm Halifax time were:
I have fallen asleep while flying before. There was another pilot and I had discussed with him that I was just going to close my eyes for a few minutes. In my opinion at least, it's better to be upfront with the other pilot about what you're doing. I felt I would be much safer if I had a short nap than if I struggled to stay awake.
I have also had it a couple of times where one of the Captains I was flying with fell asleep. He told me ahead of time that he was going to close his eyes for a bit, although he ended up sleeping for a couple of hours. I was alright with that though and the peace and quiet was nice. If there were any problems it would have been easy to wake him up and I didn't feel tired at all.
When I was flying the C207 as the only pilot, I did have one day where I had to fight very very hard to keep my eyes open. It wasn't late at night, but for whatever reason, I was feeling very tired. It was tough, but I turned on all the air vents, got cold air blowing, tried to sing to myself - anything to keep me awake. It worked, but it can be tough sometimes.