There have been many days where I've run strong on little to no sleep. Hell, about two weeks ago I was in the gym, and hadn't slept for 36hours. I still busted through the workout, but when I crashed, I crashed hard. I can't even begin to tell you how many 24-36 hour shifts I've pulled in my day. I remember coming into work, getting briefed for 3 hours, driving 12 hours to do a job, did the job that took about 6 hours to finish, then drove back another 12 hours. When we stopped for fuel, I would sleep while my vehicle was being topped off. I would shut the engine off, wedge my elbow in the steering wheel, and be dreaming before my right-seat woke me saying we're full, time to roll out. I would do the same at red lights, and be dreaming before the light turned green. Funny how a 2 minute power nap can keep you going for hours.