It appears that the old adage "the early bird catches the worm" holds true for job interviews, exams and driving tests.
Danish researchers have found cognitive function, or an individual's memory and attention span, diminishes throughout the day.
They looked at the exam results of school children and found that, for every hour earlier a test was held, scores improved 0.9 per cent.
Nevertheless, one way to mitigate the effects of waning cognitive function throughout the day is to take a break. The researchers found taking a 30-minute break could actually improve average test scores by 1.7 per cent.
"We suggest, and find, that the time at which students take tests affects their performance. Specifically, we argue that time of day influences students' test performance because, over the course of a regular day, students' mental resources get taxed," it said.
"Thus, as they day wears on, students become increasingly fatigued and consequently more likely to underperform on a standardised test."
The study was based on test data for all children attending Danish public schools between school years 2009/10 and 2012/13, and looked at how the time of the test affects performance.