Researchers tracked patients who underwent gallbladder removals at a California hospital, The Toronto Globe and Mail reported. They found fewer complications in patients after 2003, when residents were limited to an 80-hour work week.

Before 2003, about 1 percent of patients who underwent laparoscopic cholecystectomy procedures suffered from bile duct injuries and 5 percent from other complications, the study published in the Archives of Surgery said. After 2003, .4 percent had bile duct problems and 2 percent other complications.

Before limits were set on residents hours, some were on call as much as 120 hours a week.

"Up until our study, there have been no studies showing that patient outcomes have improved with the new duty-hour restrictions," Christian de Virgilio, a professor of surgery at the University of California Los Angeles medical school told the newspaper.

Critics even argued that residents were being shortchanged by the time limits.