Alright, so what are these feelings of well-being? If you want to know how this works on a chemical level, we'll break it down for you. Caffeine is roughly the size and shape of a neurotransmitter called adenosine. When it enters your body, it can block adenosine from entering adenosine receptors, changing the balance of other chemicals in your brain. https://www.sbnation.com/users/thomasgoode1