Most of the time I sleep around 8 hours, but I feel best rested if I can get 8h30 of sleep. It depends on multiple factors though, for example when I was still a student and was going through exams, I had to sleep allot more to get all the information processed and stored in my head. On a regular day with no real studying I could do with allot less sleep.
Now I get up around 8h in the morning, yet often I still feel sleepy since it's still pretty dark outside here in Belgium. The sun only comes up after 8h30! In summer it's allot more easy for my mind and body to get up early, and I often step out of bed with a big smile!
Damn winter and the strange human-made clock that doesn't correspond to the seasons, at least during this time of the year.