David Asch’s Perspective Paper and Audio Interview in the New England Journal of Medicine discusses the change of duty-hour limits in the revised common program requirements for residents released by the Accreditation Council for Graduate Medical Education (ACGME). Using results from randomized controlled trial studies, ACGME extended permissible work shifts for first year residents from 16 hours to 24 (limits already in place for residents in year 2 and beyond), permitting more within-shift flexibility. The two concerns driving the work hour shift policies are sleep deprivation and more patient hand-offs between residents. Both concerns are addressed and the study of large-scale results are highlighted in this paper.