Jolts of energy from caffeine

The explanation behind the surge of energy you get from drinking coffee is: caffeine blocks the receptors that are meant to be for adenosine.

Adenosine plays a number of bodily functions, but during our bodies' waking hours it builds up in the receptors which causes us to feel sleepy and less alert. So, when we intake caffeinated drinks, the caffeine blocks the receptors that are meant for the adenosine to build up and also could trigger the release of adrenaline.