Effect of Reducing Interns' Weekly Work Hours on Sleep and Attentional Failures

Lockley, Steven W.
Cronin, John W.
Evans, Erin E.
Cade, Brian E.
Lee, Clark J.
Landrigan, Christopher P.
Rothschild, Jeffrey M.
Katz, Joel T.
Lilly, Craig M.
Stone, Peter H.
Aeschbach, Daniel
Czeisler, Charles A.

For the Harvard Work Hours, Health and Safety Group
From the Divisions of Sleep Medicine (S.W.L., J.W.C., E.E.E., B.E.C., C.J.L., C.P.L., D.A., C.A.C.), General Internal Medicine (J.M.R.), Infectious Disease (J.T.K.), Pulmonary and Critical Care Medicine (C.M.L.), and Cardiology (P.H.S.) and the Internal Medicine Residency Program (J.T.K.), Department of Medicine, Brigham and Women's Hospital and Harvard Medical School; the Division of Sleep Medicine, Harvard Medical School (S.W.L., J.W.C., C.P.L., D.A., C.A.C.); and the Division of General Pediatrics, Department of Medicine, Children's Hospital Boston and Harvard Medical School (C.P.L.) - all in Boston. Address reprint requests to Dr. Czeisler at the Division of Sleep Medicine, Department of Medicine, Brigham and Women's Hospital, 221 Longwood Ave., Boston, MA 02115, or at [email protected].

New England Journal of Medicine 351(18):p 1829-1837, October 28, 2004. | DOI: 10.1056/NEJMoa041404

Background

Knowledge of the physiological effects of extended (24 hours or more) work shifts in postgraduate medical training is limited. We aimed to quantify work hours, sleep, and attentional failures among first-year residents (postgraduate year 1) during a traditional rotation schedule that included extended work shifts and during an intervention schedule that limited scheduled work hours to 16 or fewer consecutive hours.

Methods

Twenty interns were studied during two three-week rotations in intensive care units, each during both the traditional and the intervention schedule. Subjects completed daily sleep logs that were validated with regular weekly episodes (72 to 96 hours) of continuous polysomnography (r=0.94) and work logs that were validated by means of direct observation by study staff (r=0.98).

Results

Seventeen of 20 interns worked more than 80 hours per week during the traditional schedule (mean, 84.9; range, 74.2 to 92.1). All interns worked less than 80 hours per week during the intervention schedule (mean, 65.4; range, 57.6 to 76.3). On average, interns worked 19.5 hours per week less (P<0.001), slept 5.8 hours per week more (P<0.001), slept more in the 24 hours preceding each working hour (P<0.001), and had less than half the rate of attentional failures while working during on-call nights (P=0.02) on the intervention schedule as compared with the traditional schedule.

Conclusions

Eliminating interns' extended work shifts in an intensive care unit significantly increased sleep and decreased attentional failures during night work hours.

N Engl J Med 2004;351

1829-37.