While students gather tonight in front of common room televisions to watch medical residents on ABC’s “Grey’s Anatomy” sleeping around, a new Harvard study casts doubt on whether the characters’ real-life counterparts are sleeping much at all.

Charles A. Czeisler ’74, the Baldino professor of sleep medicine, has coauthored a report published this week in the Public Library of Science Medicine that highlights the adverse effects of extended-duration shifts on residents working in hospitals.

According to the report, residents who work just one “marathon” shift of more than 24 consecutive hours a month are three times more likely to commit at least one significant fatigue-related error, and those who work more than five such shifts are seven times more likely to commit errors.

The number of mistakes that result in the death of a patient jump 300 percent among residents who work more than five of the marathon shifts per month.

Czeisler characterized most of the fatigue related mistakes as “slips and lapses,” which include giving a miscalculated dose, ordering a medication a patient is allergic to, and trying to do a procedure on the wrong side of a patient.

Czeisler based his findings on a Web-based survey he conducted of 2,737 residents during their first post-graduate year.

Residents are actually scheduled for long shifts in order to minimize diagnostic errors, but in a study Czeisler published two years ago, he found that serious diagnostic errors actually increase 464 percent among residents working shifts of more than 30 hours.

The Accreditation Council for Graduate Medical Education (ACGME), the body that accredits U.S. residency programs, has set standards that residents should work no more than 80 hours per week. But according to the president of the Committee of Interns and Residents, Simon Ahtaridis, the ACGME fails to enforce its own rules.

Ahtaridis, whose group is affiliated with the Service Employees International Union, compared ACGME’s method of surveying residents to “the IRS passing out a survey to citizens asking ‘did you cheat on your taxes?’”

Yet a spokeswoman for ACGME, Julie A. Jacob, said that overall compliance with the group’s current standards are high.

Despite the risks involved with sleep deprivation among residents, the report recognizes that extended shifts remain a “cornerstone of American postgraduate medical education.”

Both Czeisler and the Committee of Interns and Residents support legislation that would change the number of hours that residents work. A bill proposed by State Senator Richard T. Moore, a Democrat, that would limit the maximum number of consecutive work hours to 10 for high-intensity jobs. Residents who work these extended shifts “are putting themselves and their patients at risk,” Czeisler said.