How about drinking glucose intravenously before the exam?

Some benefits, drinking some glucose before the exam can quickly provide energy to the brain, and the attention will be more concentrated. We all know that the brain needs to consume a lot of energy, which is provided by glucose. After eating, we need to digest it to supplement the glucose we need, which takes time. If glucose is insufficient, we will lose our attention, which is why most people will not concentrate in the last class.

This is what our university teacher said and his experience. He is a doctoral supervisor in food science. But I have never tried it myself. I think it is useful.