According to new research patients who undergo surgery in the morning are less likely to suffer complications compared to counterparts who go under the knife in the afternoon.
The researchers at Duke University in the US said that l changes in the body's pain levels during the day and staff fatigue are the most likely reasons for the inconsistencies.
The results of more than 90,000 operations were studied to see which times of day produced the most adverse events – classed as issues such as vomiting, prolonged sedation, wound infection, dangerous changes in blood pressure and operating room equipment problems.
"We found that adverse events were most common for operations starting between 3pm and 4pm," Dr Wright, of the Duke University Human Simulation and Patient Safety Center, told the BBC.
Lead researcher Dr Melanie Wright added: "Healthcare is a 24-hour-a-day business, and it is not unexpected that factors such as fatigue, circadian rhythms, personnel shift changes and scheduling may affect patient care over the course of a day."