Learn what caffeine actually does to your body. While you probably know that caffeine can keep you awake, you may not understand how the substance actually works. Myths abound when it comes to caffeine, and its effects vary from person to person. By understanding how caffeine works, you can use it more efficiently. How It Stimulates You While you’re awake, the neurons in your brain fire away and produce a compound called adenosine as a byproduct. Adenosine is constantly monitored by your nervous system through receptors. Typically, when adenosine levels drop and hit a certain low level in your spinal cord and brain, your body will signal to you to start relaxing to prepare for sleep….