A recent Institute of Medicine (IOM) report recommended significant changes to resident physicians' work hours to improve patient safety. These recommendations included eliminating extended duration shifts or scheduling nap times during extended shifts, decreasing resident workload, and strictly adhering to the 80-hour weekly work limits originally implemented in 2003. The implementation of the IOM recommendations would cost teaching hospitals approximately $1.6 billion, according to this analysis. However, due to a lack of clear evidence on the safety effects of duty-hour reduction, the authors were unable to accurately estimate the cost savings to society if adverse events were reduced. The accompanying editorial notes the relative lack of evidence supporting additional duty-hour reductions and calls for further study of the relationship between duty hours, handoffs, and patient safety.