Who would've thunk it? As It turns out, residents are not machines. If you schedule them to work for 24 hours or more on a regular basis, there's a pretty good chance they'll hurt someone out of sheer fogginess. Right now, medical residents may be asked to work shifts that run as long as 30 hours, as often as twice a week. To see what impact this is having, Harvard Medical School researcher Charles Czeisler and a group of colleagues conducted a monthly survey of 2,737 first-year residents asking about their schedule, sleep and days off, as well as medical errors they'd made. Their research was funded by HHS's Agency for Healthcare Research and Quality (AHRQ)and the CDC's National Institute for Occupational Safety and Health. The study found that that when students worked five super-shifts in a single month, the risk of making a fatigue-related mistake went up a staggering 700 percent. Even more concerning, the risk of making an error that killed a patient increased 300 percent. Despite these findings, some industry figures contend that scheduling such shifts is necessary at times, to provide continuity of care throughout a surgery process, for example.