Well actually, one justification I read is that it reduces mistakes due to reduced patient turnover; in other words, info missed during increased number of patient turnover may harm more than a doctor being tired. No idea how true this is though.
Not true, or maybe you are misunderstanding.
It's not about "patient turnover", it is about patient hand off. We have the responsibility to signout or "give handout" of the patients we take care of (like giving the summary of the patient, what needs to be done tonight, etc). Often times during this process, some things get lost in communication which can lead to delay in care or a bad outcome. If you shorten the number of hours per shift for each resident, then there will be more sign outs, and more information gets lost in the process.
The culture nowadays is shifting to less 24 hour calls. But it really does decrease the amount of learning and clinical training if they don't do 24 hour call. You really do in fact learn more and become more independent and build confidence in your skills if you work at night time because of decreased support staff. You will still have one supervising attending watching you, but you are limited on your resources to call, so you triage and figure out how to prioritize. Residents learn on their feet when they do this and it is what makes them competent physicians. Nowadays these residents don't even know how to order the proper dose of antibiotics and they waste my time and call me asking what dose to give, instead of spending time to look it up.
Getting rest or sleep really depends honestly. If you have a quiet night with nobody calling you, then good. If you have to see and deal with a sick patient, then you work it through.
Frequent hand offs lead to poor continuity of care for residents and overall worse training.