I missed a monster on opening day once.
I was just worn out from staying up late and not getting enough sleep. I had stayed up late 2 nights before getting ready. Then on the Friday before, we stayed up late partying and was just too anxious to sleep anyways.
So when 5 AM rolled around on opening day I just didn't have much in the tank. I dozed off waiting for the sun and woke up about a hour after sunrise. I opened my eyes and saw a flash of deer flesh through the trees. It shook me awake and I tried to get it in the scope, but was just too slow and groggy.
Later after the hunt, my wife had told me she saw a monster headed my way but couldn't get a shot off.
Since then, I have learned to get my gear together a few nights in advance and make sure I get a good nights sleep on Thursday at the very least.