And a Couple of Other Things
So there you are sitting a dozen feet or more above the ground with a loaded rifle in your hands. Presumably, you have a safety belt on so that you will not tumble out of the stand if you fall asleep. But while the belt will keep you in place, it will not keep your rifle from falling if you relax your grip, and a cocked, loaded rifle stands an excellent chance of going off if it falls. If you feel like you have to catch a few Zs, unload the rifle, lower it to the ground, climb down, and take a nap. You won't get any deer, but you won't kill yourself or someone else.