Dr. Sam Ko says resident work hours should be limited to 40 per week . Via Twitter, I warned him that I would rebut his assertion.
Without any data or references except a tangential one, he bases his opinion on four premises.
1. Residents will be happier and nicer to patients because they will be less stressed. There is no proof that this is so. In fact, a recent paper  in JAMA Surgery says about one-third of interns who work a maximum of 16 hours per day “demonstrated weekly symptoms of emotional exhaustion (28%) or depersonalization (28%) or reported that their personal-professional balance was either “very poor” or “not great” (32%).”
And “at the end of their intern year, 44% [of interns] said they did not believe that the work hours limits led to reduced fatigue.” This is not a very resounding confirmation of the theory that reduced work hours leads to happier or better rested residents.
2. “But we did it so you have to do it to.” Under this heading, Dr. Ko says, “We are busier than they were 20-30 years ago. Before they probably got more sleep and had less patients in the hospital.”
With the exceptions of more paperwork and the burden of the electronic medical record, I’m not so sure residents are busier today, but if they are, what’s making them busier is reduced work hours. This recent paper  from JAMA Internal Medicine concluded the following: “Compared with a 2003-compliant model, two 2011 duty hour regulation–compliant models were associated with increased sleep duration during the on-call period and with deteriorations in educational opportunities, continuity of patient care, and perceived quality of care.”
The supposition that there were fewer patients in the hospital 30 years ago is incorrect. When I was a resident over 30 years ago, cholecystectomy patients stayed in the hospital for 4 to 6 days. Even herniorrhaphies stayed 1 or 2 nights. Day surgery was in its infancy. Patients could be admitted for workups which are now done as outpatients. These people all needed H&Ps, had to be rounded on daily and notes had to be written. We had to draw routine and stat bloodwork and start IVs ourselves, we often transported patients to radiology and the OR. I could go on.
Dr. Ko is right about one thing. We did get more sleep when we were on call because we weren’t cross-covering many patients that we didn’t know very well. The abomination known as “night float” did not exist.
With the exceptions of more paperwork and the burden of the electronic medical record, I’m not so sure residents are busier today, but if they are, what’s making them busier is reduced work hours. As a result, I don't think resident training hours should be limited to 40 hours per week.