It's not all on a one-night basis. Depends on how much sleep I've had in a two or three night period. For instance,
I'm getting up at around 5:30 am to get some fishing in before work tomorrow, but I've had a good 8+ hours of sleep the last few nights. I should be able to get up early have a full day and not go to sleep too early and feel fine the next day.
If I haven't been getting enough sleep, I can't get up early to save my life.
I guess I'd have to say I need aroun 7-8 hours of sleep on average. If I get more than that in, I can get up at ungodly-early hours.