I need atleast 9 hours to make it through the day without feeling lethargic and yawning all over the place. I have also found that I am much funnier when I'm well rested. How is it possible that some of my friends claim to need only 6 hours, they must be walking zombies (maybe they just don't know what being fully rested feels like). How much do you sleep? Anyone else concerned about not getting enough sleep 3rd/4th year in medical school, residency?