For doctors-in-training, long hours and a lack of sleep have long been considered rites of passage into the world of medicine. Now, in the largest Canadian study of its kind, researchers have found the gruelling schedules of medical residents can pose a major risk to their health.

The National Steering Committee on Resident Duty Hours has just released the first comprehensive report on how much fatigue is too much for doctors who have completed medical school and are now training in hospital residence programs under the supervision of experienced physicians.

The report concludes that very long shifts of 24 hours or longer are too hard on the physical and mental health of residents, and that such shifts need to be avoided, except during unusual circumstances.

But it also says that setting limits on work hours is not the sole solution to resident fatigue.

While Canada’s 12,000 medical residents have traditionally worked lengthy shifts, it’s a practice that has come under increasing scrutiny. In 2011, for example, a Quebec labour arbitrator ruled that the 24-hour shifts endanger the health of residents. Now, doctors in training in that province can work no more than 16 hours continuously.

This report stresses that regular 24-hour shifts are not acceptable and that very long hours also have an impact on the health of residents, says Dr. Kevin Imrie, a lead author of the report and physician-in-chief at Toronto’s Sunnybrook Health Sciences Centre.

“They have an impact on their physical, mental and occupational health,” he told CTV’s Canada AM Thursday, speaking from Ottawa.

Research has shown, for example, that overtired residents are at greater risk of accidents with needles, as well as car accidents on their drive home after work.

But rather than creating specific limits on the number of hours that should be worked in a single shift or in a work week, the report recommends “fatigue risk-management” strategies to ensure residents are getting the sleep they need.

Imrie says restricting duty hours will neither improve residents’ wellbeing nor improve patient safety.

“We found that work hours are a very important component of fatigue, but it’s not the whole story,” Imrie said. “We’re saying those longest hours need to be reduced, but we’re not pushing for one magic number that applies across the board. In fact, we feel it should be tailored to the circumstances.”

The report notes there are huge differences among the delivery of health care across Canada, depending on such things as hospital size. As well, different medical disciplines require varying kinds of training, and these difference are too great for a “one size fits all.”

There are other important factors that influence fatigue, such as the workload on residents and well as the effects of shift work and working at night.

The report points out, though, that there are often advantages to having residents work long shifts. For example, it reduces the number of shift handovers, when patient information has to be passed from one care team to the next and when errors often occur.

“Without careful planning and resource allocations, there is a risk that resident duty hour regulations could inadvertently decrease safety and quality of care through factors such as increased handovers, discontinuity of care, and decreased trainee supervision,” the report authors write.

While it might seem intuitive to assume that fatigued residents increases the risk to patients, the good news, Imrie says, is that it doesn’t appear as it patients are affected. That’s mostly because a medical resident is usually just one of many health professionals who care for any one patient in hospital.

“Residents are part of a larger care team, with a lot of checks and balances in the system that help prevent and manage that risk,” Imrie said.

Dr. Joshua Tepper, the vice-president of education at Sunnybrook, says that the culture of medical education is changing just as health care itself has changed.

“One of the great recommendations is that we need to think differently about our education system,” Tepper told CTV News Channel.

“Things have changed a lot in health care and that means our education needs to change as well. What happens in a hospital at night today is very different from used to happen just a few years ago, as technology has changed and medical knowledge has changed.”

Imrie says because the report authors include representatives of the bodies that accredit residency programs, including the Royal College of Physicians and Surgeons of Canada, and the College of Family Physicians of Canada, there is already agreement on a number of the key issues and he is confident the changes recommended in the report can be implemented quickly.

“There are some things we can do right away, now, centrally. Our certifying colleges… plan to move directly on with a number of these recommendations,” Imrie said.

“But we’re also working with our provincial partners and we’re confident that we will see change.”