I suspect a lot depends on your natural body rhythms. I'm a morning person, and if I don't get to sleep well before that, I don't generally get 8 hours, or 7 even. Unfortunately, lately I've had major trouble getting to sleep, which means I'm running on short shrift there! (This even with trying to get out for a decent walk every day, adequate sunlight earlier in the day, etc.)
But my dh wakes rested much later than me, and seems perfectly happy going to sleep later and waking later. (He also seems to need about an hour more than I on average -- if either of us could sleep well!)