As I mentioned in another comment, the Goenka courses actually easily accommodate up to 9 hours of continuous sleep at night, from 9:30PM to 6:30AM. The pre-breakfast meditation is encouraged, but entirely optional. You could even nap for another hour after breakfast. There's also an hour to hour and a half of nap time after lunch.

I personally get 8-10.5 hours of sleep a day when doing a Goenka course. I go to bed at 9:30, have an alarm that wakes me up at 5:30, nap after breakfast from 7 to 8 and nap again after lunch from 11:30 to 1PM.