How are you going to go out every night if you go to bed at 9 or 10?
Actually, I have a serious point. Preparing for and doing well in class is just 1 facet of business school. Another very important facet is recruiting - after all, would anyone be at b-school if they weren't looking to improve themselves professionally? Anyhow, a lot of important stuff takes place later in the evening. Cocktail hours and dinner with recruiters are the obvious concerns, and you want to be at your best during these hours. Also, networking with fellow classmates in a casual setting is probably really important as well.
I think the only real solution is just to cut out sleep as much as possible.
Therein lies the dilemma. We can't go to class unprepared yet we also need to be able to schmooze with all the other VCapitalists and consultants during the after hours.
As for getting in "face time," I have been attending events for the first hour or so, then I covertly sneak out the back door when nobody's looking. I just can't stay awake after 9pm anymore.
The good thing about waking up early is that I can also get one or two workouts in at the IMA, where, believe it or not, some of my classmates like to socialize at 6am!!