For brain-intensive work you need at least 6 if not 7, optimally 8 hours of sleep per day. What you're describing - sleep from 2:30 to 7:30 - is a 5h sleep sche

For brain-intensive work you need at least 6 if not 7, optimally 8 hours of sleep per day. What you're describing - sleep from 2:30 to 7:30 - is a 5h sleep schedule. If I do that, after the 3rd day, I'd had troubles concentrating on anything. When I was in the army, I found myself into a situation where for several reasons I managed to sleep 4 hours in 3 days. In the 3rd day, I had to stay awake until 14:30 (that was the time my service was about to end, which would permit me to sleep for 6 hrs uninterrupted). I remember that from 6:00 to 14:00 I was literally hallucinating. The effect was so strong, that I still remember vividly the dreams I had over that 6 hours. I had to be sitting on various desks to perform some or no (real) work at all. I was literally falling asleep on the chair. My lieutenant was trying to keep awake somehow until 14:00, in order to make me avoid jail-time in case his superiors realize my real condition. I wasn't able to pick up a conversation without falling asleep. Even 2 seconds of closing my eyes, would immediately indulge me into a sort of a dream, involving the people around me. One of the few things I've learned in the army was that I can be operative for 8-10 hours if I sleep 4 hours per night. Then I need to get some sleep, otherwise I switch in dumb mode. After the 3rd day, I start hallucinating :-)