Learning States
To the point made by robgt350...
Back in Stone Age Psych Classes, we studied 'Learning States'. To cut right to it, the Theory was that if you had a mild buzz on during Classes, you likely would do better with a mild buzz on come time for Tests.
We had the full Honor System at this small, Lib Arts College. Take a Test anywhere you want, including outside the Classroom. I ducked into the Restroom while taking a Test in Class, only to hear this repeated 'clicking' noise. It was a Guy I kinda knew, sitting on the Can [as a Chair], and flicking this little Pen Knife incessantly while he took the same Psych Test.
Turns out, he was 'Speeding'. He'd done Speed during much of Class, and was doing so during this Test in accordance with the idea to be in the same Learning State during Testing as you were in during Classes.
He did fine on the Test, I recall. I don't advise this Practice, obviously, but there might be something to this whole 'Learning State' concept. Info absorbed is stored differently; Neurons fire differently; and so on...