Even during Viaweb I still slept 8 hours a night (roughly 3-11). The most productive people rarely have more than 6 hours or so of really concentrated work per day, except in emergencies. If you can ensure you get that every day, you don't need to economize on sleep.

My way of getting those 6 solid hours was a common hacker solution to the problem: I used the hours between 9 pm and 3 am, when no one could interrupt me.