This is what they should have taught me in chemistry class at school. Maybe I would have paid more attention!
When the caffeine from coffee gets into the bloodstream, it goes to work on the brain, amplifying the effects of various chemicals. Dopamine, which works on the reward mechanisms, and noradrenaline, the body’s natural stimulant (linked with vigilance and concentration). And caffeine does all of this by interfering with a neurotransmitter that helps us sleep – adenosine.
When we take in caffeine, it blocks the receptors to adenosine, and in doing so it takes it’s place in terms of the signalling process. So normally the levels of adenosine will dictate whether we’re feeling sleepy or whether we’re feeling awake. However the caffeine comes in, takes it place, sends its signal to the brain, and that’s why we feel more alert and awake.
Now go forth and be alert.