The study showed that general surgeons who performed emergency surgery the night before planned operations did not have a higher level of medical errors or deaths then when they operated after not working overnight.
The study, which is based on records of more than 10,000 gallbladder removal surgeries in Ontario, is published in this week's issue of the Journal of the American Medical Association.
"These findings do not support safety concerns related to surgeons operating under these conditions," concluded the authors from London Health Sciences Centre in London, Ont.
In Canada and the United States, there have been moves to restrict the number of hours that residents — doctors still in training — can work without breaks. And in the U.S., there have also been calls to regulate the working hours of surgeons as well.
These findings suggest that type of move is unnecessary, said Dr. Michael Zinner, chief of surgery at Brigham and Women's Hospital in Boston.
"The key message is for us there's no need to create regulation or policy changes to limit performing surgery. There's no evidence that it makes a difference," said Zinner, a general and oncologic surgeon who co-wrote an editorial on the study for the journal.
One of the authors of the study said the results should assuage concerns of patients about to undergo surgery.
"It hopefully will make patients feel better and reassure them that their physician can still perform well, even if they were performing the night before," said Danielle Nash, an epidemiologist.
Several previous studies have looked at the issue. But they have been small studies, often looking only at the safety records of a single hospital.
In this case, the authors drew on the huge data resources of Ontario's Institute of Clinical Evaluative Sciences. They could pull up records on operations for all non-academic hospitals in the province, and use billing data to determine if the surgeon who performed a gallbladder operation on a particular day had performed emergency surgery the night before.
They then compared the outcomes of those operations to gallbladder operations the same surgeons performed on days when they hadn't worked overnight.
The study compared results from 2,078 operations done when the surgeons had worked overnight to 8,312 operations the same doctors performed when they hadn't worked the night before.
They looked for cases where surgeons started off doing laparoscopic surgery — formerly known as keyhole surgery — but then changed mid-operation to open-cavity surgery. While that switch can happen for other reasons, such a move is generally an indication that something has gone wrong with a surgery.
There wasn't a higher rate of mid-operation technique shifts among operations when the surgeon had worked the night before. Nor were there higher rates of surgery-related injuries. And when the authors looked at deaths — which are uncommon in gallbladder removal surgery — there was no elevated risk seen there either.
Story continues below slideshow:
To prove cause and effect, they would have needed to do a randomized controlled trial, where some surgeons were randomly assigned to perform when well rested and others operated while tired. But such a study would not be allowed, for ethical reasons.
So a study like this one is likely the best option there is for answering the question of what the effect of slight sleep deprivation is on surgical performance, Nash said.
She acknowledged the messaging here is complex. No one would advise surgeons to skip sleep or to over-pack their schedules.
Still, if they miss some sleep because they have to respond to an emergency the night before a scheduled operation, their performance may not suffer markedly.
"We don't want to say that for sure all surgeons can perform well when they're sleep deprived," said Nash.
"But we just kind of say it's reassuring to see that with this common surgery, on average we find that there are no greater complications when surgeons are maybe tired from performing a surgery the night before."