Sleep is actually one of the things I can do without. The problem is I just love it too much. From about 13-16 I used to get 3-5 hours every night aside from weekends. Alot of people get bitchy without it but I'm usually fine. If I don't have any food I get testy but sleep isn't a big deal. There have been plenty of times I'd get 3 and function in a full day of work. If I do get 2 hours or less I am out of it. Not angry just spaced out. I only did no sleep once when I was 15 with work and that wasn't something I want to try again.