The common perception is less hours = less tired doctors = less medical errors. However, what also is happening is that we are getting lesser-trained physicians:
The 405 regulations mean residents spend at least 25 percent less time in the hospital. As one doctor who just completed his training put it to me, a five-year surgical residency has suddenly become the equivalent of a three-year one.
The problem is one of scarcity; we could certainly have more medical safety, getting the best of both reduced hours and extensive supervision, by devoting more social resources to health care, but in a world without free lunches, we as a society might rationally prefer to spend our money elsewhere: we can’t devote 100% of GDP to rooting out the last medical error. There are cheap ways to improve medical safety, and there are expensive ways to improve medical safety, and increasing staffing levels falls in the latter category. It’s too soon to tell whether the new hour rules will be a net gain or a net loss.