@Light at end of tunnel @Matthew9Thirtyfive @SouthernSurgeon this is a shot in the dark, because I'm just a pre-med student and have no real idea what surgery entails, but here's a hypothesis:
Maybe, surgeons in-training don't need as much sleep because, while you're right
@Light at end of tunnel sleep is important in memory consolidation and etc., perhaps it's not as important in things such as the motor-coordination skills honed and required in surgical specialties? I'm not saying surgeons don't require critical thinking and so-on, but, from what I can tell, after years of practice they're usually in a state of flow during their surgeries—and at some point their mastery comes from muscle memory and etc, especially for the more routine procedures.
If that's true, then longer hours may be better than night floats, for they allow more practice of the fine-tuned motor skills required of surgeons. As for other specialties that require more diagnostic work, solving the riddles of pathology and etc, higher brain functions would be much more important, and therefore sleep as well.
Again, I could be totally wrong in my characterization of a surgeon's work, but it's just a thought.