This multicenter cluster randomized trial explored the impact of eliminating extended-duration  work schedules (shifts in excess of 24 hours) on serious medical errors made by residents in the pediatric intensive care unit (ICU). The authors found that residents in ICUs which eliminated extended shifts in favor of day and night shifts of 16 hours or less made significantly more serious errors than residents assigned to extended-duration work schedules. The authors observed that the resident-to-patient ratio was higher during schedules which eliminated extended shifts, but also that these results might have been confounded by concurrent increases in workload in ICUs eliminating extended shifts.