I've actually stayed up all day, all of the next night, and all of the next day, which I would imagine would have been over 30 hours. It's all due to sleep problems. I can't sleep all night, then have to stay up the whole next day to ensure that I don't screw up my whole schedule and sleep cycle. Not reccomended to anyone, I can tell you, but it's not like I have a choice. It's happened several times.