It’s something I worried about every time I had surgery. What if the doctor was on call the night before and was fatigued by the time I had my operation? Now research that followed the outcomes in nearly 39,000 cases here in Ontario found that patients having elective surgery during the day fare no better or worse if the doctor operating has worked the night before. The work tracked similar patients who had the same procedure conducted by the same physician, with and without a night off to rest. It found the risk of adverse outcomes from the daytime surgery was similar, even if the doctor had treated patients between midnight and 7 a.m. the night before.

The study in the New England Journal of Medicine is the latest chapter in a long debate about the effect of round-the-clock shifts on patient safety.

Nancy Baxter, the chief of general surgery at St. Michael’s Hospital and a senior researcher on the study, said the findings show that physicians are finding ways – either through scheduling or monitoring their performance – to respond to the need for emergency care without negatively affecting patients.

Critics say the study is flawed because it only shows whether the doctors worked the night before and not whether they managed to get some sleep.