The researchers analyzed the results of over 100,000 oral exams conducted at an Italian university and found a clear bell curve in pass rates that peaked at noon, regardless of the test taker's chronotype. (More on that in a moment.) Between 11 a.m. and 1 p.m. is the sweet spot; any earlier or later and the chances of passing significantly decreased. In fact, the earlier or later in the day students took a test, the less likely they were to pass.