I'm a fan of sleep and sleeping in but it seems that I'm doing perfectly fine sleeping for about 6 hours a day.
I do have a friend who feels great with just 3-4 a night and can't really sleep more. He's been living like this for decades now and seems to be perfectly healthy. He seems to be living more of life than us mere mortals every single day.
I can't imaging how much more work I would be able to do with an additional 3 to 4 hours every night. I'll probably devote them to gaming, music and learning. Or steeming! :)