I hear you. Those would be my preferred hours too. Fortunately for me, my familly doesn’t particularly think that’s a problem (or at least, I’m old enough for them to leave me to deal with it myself if it is), though of course I get teased about it. Unfortunately for me, I have work and uni to unreasonably demand I be up in the mornings. grumbles
As to how much sleep I need to start the next day feeling goodly: infinite. I never start the day feeling anything but dead. I usually must spend at least half an hour technically awake but not actually moving before I can get up. However, to be feeling decent a little while after I get up, I think I need about 5-6 hours. I can go down to 3-4 for a couple of nights without too many ill effects though. If I can I spend much longer than that in bed though. On most weekends I’m technically awake by around 8:30, but I sometimes don’t get out of bed till 2:00.