The longstanding debate over medical residents’ lengthy work hours pits patient safety advocates against those who view the practice as necessary for continuity of care, preparation for medical practice, and cost containment (Steinbrook, 2002). After years of debate, and the threat of federal regulations, the Accreditation Council for Graduate Medical Education changed its requirements in 2003 to restrict residents’ work hours to about 80 hours per week (ACGME, 2003). The policy permits no more than a maximum shift duration of 24 hours and overnight call no more than every third night.

Does this revised policy protect patients? The Harvard Work Hours, Health and Safety Study compared a schedule of about 80 hours per week (termed the traditional schedule) with a reduced schedule that eliminated shifts of 24 hours or more and kept work hours under 63 per week. The trial was conducted in intensive care units because they typically have the longest hours and the highest rates of errors.

The intervention schedule not only enhanced interns’ sleep duration and lowered their rate of attentional failures, but also reduced the rate of serious medical errors, according to two articles published in 2004 in the New England Journal of Medicine. In the first article, the investigators used a within-subjects design (n = 20 interns) and validated sleep duration by polysomnography and attentional failures by slow-rolling eye movements recorded during continuous electro-oculography. Under the intervention schedule, the article reported that residents slept nearly 6 more hours per week, and they experienced half the rate of attentional failures during on-call nights than under the traditional schedule (Lockley et al., 2004).

The second article on medical errors reported results after randomizing interns to either the traditional or reduced schedule (Landrigan et al., 2004). Two physicians who directly observed the interns without awareness of their schedules identified serious medical errors, defined as causing or having the potential to cause harm to a patient. Errors were recorded by type (medication, diagnosis, and procedure) and in terms of number, or rate per 1,000 patient days. The study covered a total of 2,203 patient-days involving 634 admissions. Under the traditional schedule, interns made nearly 21 percent more medication errors and at least five times more diagnostic errors. Overall, the unitwide rate of serious medical errors was 22 percent higher in the traditional versus the intervention schedule (P < .001) as shown in the table below. The investigators concluded that reducing interns’ hours can lower the occurrence of serious medical errors in the intensive care unit.