As a result of these requirements, primary care physicians spend more than half of their 11.4 hour workday performing data entry and other tasks, according to a September AMA/University of Wisconsin study published in the Annals of Family Medicine.

To manage, doctors often finish work at home in the evening, a part of the day known as "pajama time."

Costs To The Health-care System

Doctors' suffering can take a direct toll on patients. In a 2010 study, Shanafelt and colleagues found that the more burned out a surgeon was, the more likely he or she was to report a major medical error. Other studies have shown that burnout drives up rates of unnecessary testing, referrals to specialists and hospital admissions.

When doctors quit, it costs an estimated $800,000 to $1.3 million in recruitment, training and productivity costs, depending on the specialty.

Even when physicians don't leave, they can contribute thousands of dollars in costs each year "just as a matter of inefficient functioning," said Dr. Colin West of the Mayo Clinic.

The trend has medical malpractice experts concerned. CRICO, the malpractice carrier for Harvard University's two dozen affiliated hospitals, recently had to settle a handful of cases because doctors were too burned out to fight, even though CRICO believed it could win.

"The clinician just wanted it to go away," said Dr. Luke Sato, CRICO's chief medical officer. Sato estimates that an average breast or colorectal cancer malpractice case might cost $750,000 to $1 million to settle.

The crisis has Harkaway worried for his colleagues in Michigan, and for his profession.

"Working with doctors every day, you see it," he said. "They are just beat down."