It’s 3 p.m., I’ve been seeing patients for a few hours and I feel my focus fading. I need to stay sharp for those still to come, so I grab a snack and some coffee.

This has become my afternoon ritual during my 20 years as a primary care doctor. Now, a new study confirms that my feared “3 o’clock fade” is real — and that it could affect patients’ health.

According to the study, published in JAMA Network Open, doctors ordered fewer breast and colon cancer screenings for patients later in the day, compared to first thing in the morning. All the patients were due for screening, but ordering rates were highest for patients with appointments around 8 a.m. By the end of the afternoon, the rates were 10 percent to 15 percent lower. The probable reasons? Running late and decision fatigue.