Chicago » Doctors have steadily cut their work hours over the past decade, a new study finds, something that experts say may only worsen the health care situation.

It's not that doctors are slackers. Average hours dropped from about 55 to 51 hours per week from 1996 to 2008, according to the analysis, appearing in today's Journal of the American Medical Association .

That's the equivalent of losing 36,000 doctors in a decade, according to the researchers. And it raises policy questions amid a looming primary care doctor shortage and Congress considering an expansion of health insurance coverage that would mean more patients.

Work-hour limits for residents, or doctors in training, were introduced in 2003 and brought down the average. But when researchers removed the resident doctors from the analysis, they still found a nearly 6 percent decline in work hours.