Along with diet and exercise, sleep is one of the three pillars of health.  Yet, despite everything we know about the benefits of a good night’s sleep, doctors themselves are often sleep deprived. Especially residents – doctors fresh out of medical school, who are in their first three years of hospital training.

“The residency system as we know in the United States was really pioneered by William Halsted, who was the first professor of surgery at John's Hopkins,” says Charles Czeisler, chief of the division of sleep medicine at Brigham and Women’s Hospital.

“He was quite famous for his ability to remain awake continuously for seemingly days on end, and it was only five years ago that it was recognized that he was actually a cocaine addict," Czeisler says.

Czeisler says it's no wonder that Halsted could withstand marathon hours of work.

“But the system that he put in place has now foisted these hours on generations of physicians,” says Czeisler.  

Physicians like Susan Swords. She recalls regularly working 30-hour shifts in her first two years of residency at Cambridge Health Alliance.

“There were times I felt tired,” says Swords, “but the tired you feel when you’ve been awake that long, is sort of similar to being intoxicated.  You feel like your drunk."

Feeling drunk and taking care of patients. Swords says when morning came she would have nausea and chills. Then she would go home and pass out.  But she still felt groggy after waking up – a phenomena called sleep inertia, when the brain is awake, but not fully functional yet.  

Last year, Cambridge Health Alliance put a sixteen-hour cap on all resident work shifts, which was an answer to Swords dreams.  

“My third year I celebrated and rejoiced because I never had to do that again,” she says.

Ten years ago, Charles Czeisler and colleagues started a clinical trial at Brigham and Women’s Hospital to study how patient safety was impacted by residents’ long work shifts. 

They found that if residents didn’t have to work marathon shifts, medical errors could be reduced by a third.

“On the traditional schedule there were 36% more serious medical errors, including 460% increase rate of serious diagnostic mistakes,” says Czeisler. “So they made almost 5 times more serious diagnostic mistakes.”

This and other studies have cut down on long workdays, but only to a point. The Institute of Medicine suggested that residents not work more than 16 consecutive hours.  But the body that controls resident work hours, the Accreditation Council for Graduate Medical Education, still allows second and third year residents to work up to 24 consecutive hours.

Czeisler and his colleagues are embarking on a new, larger study, specifically looking at second and third year residents and whether their super long shifts have a similarly deleterious effect on patient safety.  

WEB EXTRA: Czeisler says the risk of having a motor vehicle crash is 168% higher for residents working marathon shifts.  In his new study of residents, infrared technology will be used to measure how tired residents are as they drive home from work. Watch "Micro-Sleep May Be to Blame for Accidents" from ABC World News Tonight with Diane Sawyer ​ to see the technology in use.