From morning coffee to afternoon tea, caffeine is so thoroughly entrenched in our daily routines and has become the world’s most widely used psychoactive substance. Caffeine is a chemical compound that stimulates the central nervous system. It accomplishes this by attaching itself to adenosine receptors in the brain. In doing so, it blocks adenosine molecules, which are responsible for slowing down the central nervous system before we sleep. The result? Adenosine cannot regulate and neurons start firing. This results in a person’s reduced fatigue and increased alertness and cognitive performance, side effects many seek by consuming caffeine.