Being neglected and unsupervised as a kid meant free reign in exploring the effects of various endurance experiments. When I was 13, I did this a few times with food, water, and sleep. First I did them separately, and by taking advantage of my mother being passed out, I got to see how long I could go without food. That lasted a week, if I recall. My memory of it went something like this:
Day 1: Not happy. Very crabby.
Day 2: Very hard to get through school day. I was starving.
Day 3: I felt real sick, weak, dizzy, and my mouth had this terrible taste.
Day 4: Felt a lot better, lighter
Day 5: Had this weird feeling of being connected to everything
Day 6: Felt very light-headed, but okay. Not hungry at all.
Day 7: Very weak... then ended fast
Day 8: Sick for the next few days
I didn't know after a fast that you are supposed to start eating lightly. I did more fasts, but most only lasted 4 days. Then the last time I tried this foolish experiment, I went 4 days without sleep, food, or water, just to see if I could do it. I have to admit, on day 3, I was so thirsty, I did start drinking water, and then I collapsed, and "forgot" I was fasting and ate (I was so mad; it was the first time I realized my brain started to "trick" my logical impulses).
I might fast again someday (there are some great resources on safe fasting), but the sleep and thirst thing... no. Never again.
But the sugar endurance test was really hard today. It was Donut Friday at work.