began, involving nearly 190 hospitals and residency training programs. The studies randomly assigned medical residents to shifts longer than specified by the ACGME regulations. A study led by the University of Pennsylvania, which will end in 2019, assigned residents in 32 medical training programs to shifts as long as 30 hours. It used 31 other programs as a control group. Despite the longer shifts, the other overall rules were still adhered to. The other study, led by Northwestern University and ending in 2015, was similar in design. Both were conducted with the approval of the ACGME. In neither study were residents and patients necessarily told they were part of a human subjects experiment and informed consent was not required, which caused some controversy. Duty hour restrictions Effects of duty hour restrictions Regulatory duty hour restrictions, in theory, should reduce the number of duty hours worked. In practice, they may not because the restrictions are not always followed. Studies to evaluate the effects of duty hour restrictions on patient outcomes have been somewhat mixed. Many of the studies rely on self-reported hours, self-reported errors, and self-reported sleep deprivation, with large opportunities for bias. More objective measures, such as tracking, perceptual tests, and blood hormone levels, are generally not used. Measurements of patient deaths and harm are often used as response variables. Many of the studies that have been done on this topic are specialty specific and so cannot be generalized to all medical residency programs. Observations on the ACGME restrictions in US The 2003 working-hour restrictions imposed in the US by the ACGME allowed many studies comparing patient outcomes before and after the reforms. They generally show little effect. This corresponds to the impressions of medical staff. One 2014 systematic review of 135 studies spanning 1980 to 2013 showed no overall improvement in patient safety but still indicated that duty hour restrictions have increased morbidity in some cases. Another systematic review of 27 studies conducted in 2015 found similar results, and a 2007 study of over 8 million hospital admissions of Medicare beneficiaries that compared mortality rate before and after implementation of the ACGME standards showed no difference in mortality. 2003 reform One study of 318,636 patients done in a Veterans Administration setting showed that work hour restrictions reduced mortality substantially for a similar set of diagnoses. Another study found that the 2003 ACGME reform restrictions were associated with a small