I need at least 8 hours, preferably 9. It's not always easy to get though.
I dated a guy who only need about 5 or 6 hours. I was so jealous because it just gave him so much more time in the day to get things done!
With how difficult it's getting to balance work and school, I think I need to forfeit my 8+ hours and start getting up earlier to get more homework done.