Does your mind feel more “fresh” in the morning? That’s because early in the day, you’re at the height of your cognitive abilities. And new research shows that’s also when you’re likely to perform best on an exam.

While afternoon exams may give students more time to cram (and sleep), researchers found that exams taken later in the day tended to yield lower scores.

The analysis revealed that for every hour after 8 a.m. the exam was scheduled, the students’ test scores on average declined around 1 percent — a drop roughly equivalent to missing 10 days of school. The students who were already performing poorly in school were most affected by varying start times.

The researchers concluded that students perform better in the morning since they are not tired from attending class and doing school-related tasks, as they tend to be later in the day, Dr. Hans Henrik Sievertsen, an education researcher at the center and the study’s lead author, told The Huffington Post in an email.

“If they have a test later in the day, they will have been in class for hours before taking the test,” he said.