Counter to what we have always believed, coffee, or any type of caffeine, does not make you feel awake and super jittery, by itself.
This is how caffeine really works:
In the simplest terms, caffeine tricks your brain into thinking it's something it really isn't. This world-renowned impersonator disguises itself as a neurochemical found in the brain called adenosine.
Adenosine is produced by neurons firing around in your brain.
Your nervous system is actively monitoring adenosine levels through receptors. Normally, when adenosine levels reach a certain point in your brain and spinal cord, your body will start making you feel sleepy. This is because your brain looks at adenosine as a sign that your brain is producing too many neurons and slows it down. There are a few different adenosine receptors throughout the body, but the one caffeine seems to interact with most directly is the A1 receptor.
When caffeine enters your body, it knows to head straight to the adenosine receptors in your system and, because of its chemical similarities to adenosine, it's accepted by your body as the real thing and gets into the receptors.
Caffeine actually blocks these receptors, and allows for dopamine and glutamate to be released freely without the receptors stopping them. These two chemicals being released will give you that rush of an awake feeling when you drink caffeine.
Let's look at it a bit simpler...