In the U.S., doctors are known for working extraordinarily long hours, seeing patients in the office and then at the hospital. But in the last decade American doctors have been either retiring or putting in shorter work weeks while fewer Americans are entering medical school.
There's a shortage of students in American medical schools and that is one of the issues. In recent years, U.S. medical colleges have graduated an insufficient number of students.
Experts say the United States needs at least 50,000 more doctors, and if nothing is done about it there could be a shortage of 200,000 by the year 2025.
The drop in the number of physicians is acute in rural areas. In addition, there are two growing segments of the population in greater need of medical care: the elderly and the uninsured, largely made up of immigrants and the poor.
So, if there's a huge demand for medical services, why aren't doctors putting in longer hours?
Professor Douglas Staiger of Dartmouth College in New Hampshire was the lead author of a study in the Journal of the American Medical Association.
"We think that probably the changing financial and competitive pressures on physicians are just discouraging long work hours," Staiger said. "They are making that last hour of work less pleasant, less rewarding."
Residents, who are hospital doctors in training, have historically worked long hours. But in 2003, their hours were cut as a result of mandated limits imposed nationwide.
Dr. Betsy O'Donnell is at Beth Israel Deaconess Medical Center in Boston. She says a shorter work week of 80 hours helps her function better. "I'm the mother of two, so I think that it enables me to balance those responsibilities much better than a 100 hour work week would probably allow me to do," she said.
At first, researchers thought the limits on residents' hours were the main reason why physicians' hours were dropping.
But the decline in hours has been throughout the profession, including doctors who do not work in hospitals.
Using data from the US Census bureau, the researchers found that doctor's hours declined while at the same time their incomes dropped 25 percent between 1995 and 2006.
The loss in income was most likely the result of cuts in private and government insurance reimbursements, the authors said.
One doctor put it this way: the less you are paid, the less incentive there is to work harder.
In addition, American students have found it difficult for decades to get into medical school in their own country. That's a prime reason for the shortage of new doctors.
The medical profession now says something must be done.
The Association of American Medical Colleges says a 30 percent increase in enrollment is necessary to replenish the supply of doctors.
For the first time in half a century, several new medical schools are planned or already opening.
But some experts worry those students won't graduate soon enough to resolve the crisis.