Interns who get just an hour more of sleep a night — and who work fewer hours — make fewer dangerous errors.

The findings come from two studies appearing in the Oct. 28 issue of The New England Journal of Medicine. Both studies are from researchers who compared a reduced-hour intern schedule to traditional intern schedules at Boston's Brigham and Women's Hospital.

On the traditional schedule, the interns worked an average of 85 hours a week — more than half of the 168 hours in a week. Those on the reduced schedule averaged 65.4 hours a week. They got six more hours of sleep a week and slept about an hour more before each shift.

The result:

—With better rest, serious intern errors dropped by 36 percent.

—On the traditional schedule, there were 56.6 percent more serious intern errors that weren't caught by others and affected the patients.

—On the traditional schedule, there were 22 percent more serious intern errors on the critical care unit.

—On the traditional schedule, tired interns made 560 percent more serious diagnostic errors than their better-rested peers.

It stands to reason that sleepy doctors would make more errors. Indeed, researchers Steven W. Lockley, PhD, Christopher P. Landrigan, MD, MPH, and colleagues note that a person who loses a single night's sleep has a drop in performance similar to a blood-alcohol level of 0.1 percent.

Yet most of the 100,000 U.S. doctors-in-training regularly work 30-hour shifts. And that's only because the Accreditation Council for Graduate Medical Education recently cut intern hours.

In an editorial accompanying the studies, Jeffrey M. Drazen, MD, notes that simply reducing hours isn't enough. Fewer hours for interns means that single doctors can't take full responsibility for patients they admit. This means that doctors will have to learn how to work in teams and that patients will have to accept team care rather than individual doctor care.

Moreover, Drazen says, hospital doctors will have to get much better at passing patient information from one intern — and from one team — to another.

"We must be more than awake — we need to be awake and informed," Drazen writes.

By Daniel J. DeNoon, reviewed by Brunilda Nazario, MD

SOURCES: Landrigan, C.P. The New England Journal of Medicine, Oct. 28, 2004; vol 351: pp 1838-1848. Lockley, S.W. The New England Journal of Medicine, Oct. 28, 2004; vol 351: pp 1829-1837. Drazen, J.M. The New England Journal of Medicine, Oct. 28, 2004; vol 351: pp 1884-1885. Mukherjee, S. The New England Journal of Medicine, Oct. 28, 2004; vol 351: pp 1822-1824. Ofri, D. The New England Journal of Medicine, Oct. 28, 2004; vol 351: pp 1824-1826.