badshotbob... I know your pain. But I've done it plenty of times and I can share a few of my "tricks" with you. A few years ago my buddy killed the nicest buck either of us had ever gotten, putting him way ahead of me in bragging rights. So I spent the next THREE SEASONS staying on stand all day, every day. It was truly awful. Thank the Lord its over now, after I finally "caught up" to him. Here's my routine for all day stays.... 1) Dont drink more than half a cup of coffee or whatever before leaving camp. Take just one bottle of water to the stand and only take small sips throughout the day. By doing this, I have managed to go all day without having to pee (but I was pretty dang thirsty). 2) Use the bathroom before going to the stand 3)Take some good high energy, high calorie snacks..I prefer a ziplock bag full of trail mix (nuts, raisins, M&Ms, etc). 4) On the stand, I occupy my mind for as long as possible by glassing everything and also looking for every sound I hear until I identify what is making it...even if I know its a squirrill or a bird. I've been suprised a few times to see a flash of deer hide through the brush. 5) When I cant take looking at leaves any more (usually about noon or so) I pull out a good paperback (there is a fantastic series of Civil War mystery novels by Owen Parry that I strongly recommend, by the way. I have read these all afternoon and then hurried back to camp so I could read some more!). I make it a point to stop and glass the area every 4 or 5 pages. I have not had reading cause me to lose a chance at a deer yet...even thought I know it will probably happen someday. The way I see it, I still have a better chance with the book in my hand on my stand than I do back at camp. Based on my experience, once I make it past 3:00 I'm fine...because then I know that with every passing minute, the odds are improving for deer movement. Cat naps are OK too, if you have a safe place to do it.
Good luck!