America’s doctors-in-training are committing serious errors as a result of being forced to work over 80 hours a week, says new research which suggests the U.S. medical community has been slow to tackle sleep deprivation in its staff.

While the side effects of working long hours with no sleep have been well documented in other professions, two studies published in Thursday’s edition of The New England Journal of Medicine show doctors still have to alter their habits.

“We need to replace the traditional system with one in which the responsibilities for patient care are shared by a team and that allows physicians to get more sleep,” Journal Editor Jeffrey Drazen said.

The new research is special in that medical interns were studied under real conditions, working in intensive care units over the course of a year.

Doctors-in-training typically work 30-hour shifts with little or no sleep. Only last year did the Accreditation Council for Graduate Medical Education mandate that interns should not work more than 80 hours per week.

The researchers, led by Charles Czeisler at Brigham and Women’s Hospital in Boston, found that interns working more than 80 hours a week committed 36 percent more serious medical errors than interns who kept a less arduous schedule.

When it came to diagnosing illness, the sleep-deprived interns made 5.6 times more serious mistakes than their rested colleagues, the research showed.

Most of the intern errors were caught by nurses, pharmacists and senior members of the medical staff before permanent harm was done.

Christopher Landrigan, another author of the study, said the length of the study was too short to prove whether all the extra errors translated into more deaths and disability.

He said the medical community has traditionally kept long work shifts in the belief that extended hours in the hospital are needed to maintain the continuity of care. “We tested that belief and found it was not true,” Czeisler said.

As part of the research, Czeisler hooked 20 interns to eye movement monitors to look for signs of sleepiness. During overnight shifts, interns on the longer schedule were twice as likely to nod off.

“They were caring for patients, and suddenly their eyes started rolling around in their sockets,” Czeisler told Reuters. “Instead of being at the top of their game, they were just holding on by the fingernails to try to stay awake.

“The question is, is that a safe mode in which to have your physician operating when caring for patients in the hospital?”

A 2002 National Sleep Foundation poll found that 86 percent of Americans said they would be very concerned if they knew that their surgeon had been on duty for more than 24 hours before taking care of them; 70 percent would ask for a different surgeon.