Context: Further restrictions in resident duty hours are being considered, and it is important to understand the association between workload, sleep loss, shift duration, and the educational time of on-call medical interns.
Objective: To assess whether increased on-call intern workload, as measured by the number of new admissions on-call and the number of previously admitted patients remaining on the service, was associated with reductions in on-call sleep, increased total shift duration, and lower likelihood of participation in educational activities.
Design, setting, and participants: Prospective cohort study of medical interns at a single US academic medical center from July 1, 2003, through June 24, 2005. Of the 81 interns, 56 participated (69%), for a total of 165 general medicine inpatient months resulting in 1100 call nights.
Main outcome measures: On-call sleep duration, estimated by wrist watch actigraphy; total shift duration, measured from paging logs; and participation in educational activities (didactic lectures or bedside teaching), measured by experience sampling method via a personal digital assistant.
Results: Mean (SD) sleep duration on-call was 2.8 (1.5) hours and mean (SD) shift duration was 29.9 (1.7) hours. Interns reported spending 11% of their time in educational activities. Early in the academic year (July to October), each new on-call admission was associated with less sleep (-10.5 minutes [95% confidence interval {CI}, -16.8 to -4.2 minutes]; P < .001) and a longer shift duration (13.2 minutes [95% CI, 3.2-23.3 minutes]; P = .01). A higher number of previously admitted patients remaining on the service was associated with a lower odds of participation in educational activities (odds ratio, 0.82 [95% CI, 0.70-0.96]; P = .01]. Call nights during the week and early in the academic year were associated with the most sleep loss and longest shift durations.
Conclusion: In this study population, increased on-call workload was associated with more sleep loss, longer shift duration, and a lower likelihood of participation in educational activities.