I've heard this argument before, and always thought that it was pretty dumb (no offense.) All you are arguing for is that working during the nighttime provides a better learning experience than does working during the daytime. So just assign interns to night float then. How is this an argument for 30-hour shifts (i.e. call?)
The biggest argument is that once a patient is admitted, all the
decision making therapeutics or additional diagnostics happen in the first 24 hours. If you admit a patient at 8pm, go home at 11, and cant come back in until 9 the next morning (10 hours out of hospital) you've missed half the admission.
It isn't working at night or working during the day. Its working with that patient, from the start to the finish. After day 1, its all social work and placement, or "fellow, help me, please!" The first 24 hours are crucial to find out where you did it right, where you did it wrong, and to force you to clean up your own mess (i,e, not leave one).
Let me ask you this. have you ever come in the morning after as a medical student to find that your patient has changed beds, maybe even upgraded to the unit? How about something less severe. Medications had been changed, new labs you didnt know were coming in came in (or worse, your attending asks for the results and you didn't even know they were ordered). You weren't part of the medical decision making and had no idea what had happened. Happened to me. Alot. Who were the people making those decisions? The interns. Those decisions were made sleep deprived, but with a resident and attending safety net.
Look at it from the float side. Ever get a patient where you were all like "crap, what is going on with this guy, and why is the patient with a PE stroking right now?" Fixing people's messes or beign horrendously confused on patients that aren't yours isn't good training. You just keep them alive until the next morning when the "real team" comes back in and says "oh yeah, I knew about that, we weren't going to touch it, we already ruled out that..."
Lets go a little farther than residency. When you're a private medicine attending at a local hospital, working 7 on 7 off, you've got to admit or consult whatever comes in (unlimited number) and round on your census of 27 patients. Sleep deprived. Remember when you got that training in residency? Oh yeah... thats right.
But you'll say you get it as a resident! PGY-2! When you're more experienced, when you've had more time in the hospital. More time as a 5th year medical student, you mean. So now, the less-experienced pgy-2 is left alone in the hospital, has never been on his own before, and is expected to know what to do with one less safety net. Only him and the attending now. Oh, and you're also supposed to manage medical students and the interns below you.
Maybe it will be awesome. Maybe it will be the best thing imaginable. I for one am against the change. As some one who has done a many no-sleepers, 2pm on day two does suck, but I learned a hell of a lot about my patients and the flow of the hospital while I was at it.