The Economist has this article about a study recently published showing that when blood sugar levels are low, people use more intuition to make decisions. You know, when you have been thinking hard about something for a while and then there is one last decision that you just can’t be bothered with? That is what the scientists were studying.
The scientists got a bunch of students to do a mentally taxing task and then gave half of them lemonade with sugar and half lemonade with another sweetener. Using a psychological trick (read about it in the article if you want) the scientists were able to show that those who had been mentally worked and not given sugar were more likely to make decisions using intuition instead of reason.
So it turns out that you really should take food into exams and that you really shouldn’t make important decisions on an empty stomach…