Scheduling a colonoscopy in the morning may increase its accuracy.

A study reported in the American Journal of Gastroenterology found that doctors located polyps in 26 percent of colonoscopies done in the morning, but only found 21 percent in procedures done in the afternoon.

Fatigue may account for the difference; doctors who only worked half a day found polyps in 27 percent of procedures whether they were done in the morning or afternoon.

Another study found that for each hour that passed during the day, the number of polyps doctors found declined by 4 percent.