Be it a simple coffee or a tablet of Excedrin, caffeine is in almost everyone’s life. Even if you aren’t the kind of student to ingest some sort of caffeinated beverage daily, it probably enters your system in some form or the other — be it chocolate or simply a soft drink. Regardless of how it enters your body, the most perplexing yet advantageous thing about the stimulant is its effect on your body. In celebration of National Espresso Day, here is the Clog’s scientific breakdown of how coffee works in the body.

As a stimulant to the central nervous system, caffeine enters your blood and travels through your body. When it gets to your brain, the normal brain chemistry experienced when drowsy is changed to result in wakefulness. Simply put, caffeine enters your brain, so it is physically difficult, if not impossible, to get drowsy and go to sleep.

Going down to a molecular level, caffeine and adenosine (the molecule in charge of making you drowsy and sleepy) have similar structures, as they are formed from the same kinds of atoms. What this means for your brain is that adenosine doesn’t bind to your adenosine receptors, which would tell your body that it’s time to sleep. Instead, caffeine molecules perform the same chemistry that adenosine would and bind to these receptors. With your brain saturated by these caffeine molecules, the drowsy molecule, adenosine, can no longer act.

Since adenosine isn’t working, your brain can’t tell your body to slow down and get ready to rest, leaving you awake and more productive. Additionally, caffeine also makes your neurons, the cells in your brains, work faster and stimulates them to send messages to your body more quickly. Another part of your brain, the pituitary gland, understands this to be an emergency. What happens next is a release of adrenaline.

With the adrenaline making your heart beat faster and the lack of drowsiness filling you, it’s easy to understand why caffeine works. While this explains how coffee can help you be more productive, its addictive nature remains a mystery.

Another effect of this stimulant is the boost of dopamine in your body. Since caffeine makes your brain cells work faster, it also stimulates the “happiness centers” of the brain, causing a release of dopamine. Known as the happy molecule, dopamine’s chemistry in the brain works to make you feel better and is the main molecule you typically associate with happiness. Since caffeine directly leads to its release, the brain and your body relate the two. This correlation is the foundation of caffeine addiction.

With this knowledge in hand, we hope that it helps you make decisions about your caffeine consumption on National Espresso Day!