Tired? The importance of letting ideas marinate and percolate through sleep
nytimes.com
nytimes.com
I am glad you realized you needed your share of sleep.
On the other hand, some of my finest moments of clarity have come after all-night cramming sessions. It's as if you fatigue all the usual pathways and are open up to entirely new ways of seeing things.
Don't confuse working on a problem for a long time, understanding it very clearly with having the idea in your head and regurgitating a solution in one long stint. Woz emphasized this in his 2005 Startup School talk. Understanding an idea so completely in your head you can simplify it no more.
Edit: here's a wiki article about the topic: http://en.wikipedia.org/wiki/Sleep_and_creativity
Every once in a while in the past, when I was working on my own project, I've done it to the point where I would sleep from 2am to 1pm, and the next time living in the dark for a day due to going to bed around sunrise (5am) and waking up at sundown (6pm), and so on. Eventually, I would have a normal schedule again. :) This was when my only focus was on writing code for my software and working out, period. Since my software became better every week, and I grew stronger, bigger, and faster as well, my goals were pretty much met and I was happy.
I like my current life as a student, due to the social aspect of learning from, and working with, others. But I am nowhere near as productive at developing my own software on a daily basis nor working out as I was when those were my only two goals. However, I understand that it has only been a few weeks, and I will be able to figure out how to introduce software and personal development into my schedule as I get more used to the demands of my classes. And even though I won't be able to dedicate as much time as I could before, I have the experience and confidence to get in shape and create software more efficiently, as well as the benefit of a being around lots of potential users.
So sleeping did not impede him working 24 hours a day. It actually helped.
Other problems demand several passes of experimentation. For those it's easier to try a quick test during the day, think about it while doing other things, and then wake up with the (possible) solution the next day.