From what I can tell after a certain amount of time awake you build up "rest credits" which u can use to sleep or w/e.
http://www.tomsguide.com/us/NVISION-LAN-Party,news-2512.html"Thankfully the players were allowed to take breaks and were given a 10 minute rest period for every straight 60 minutes played. This rest period could be saved up so six hours of play would get you an hour of rest. NVIDIA was also kind enough to provide free food and drinks to the gamers. To top it off, BAWLs was giving away pallets of their caffeinated energy drink."