Why caffeine keeps us awake

In the human body, caffeine acts as a stimulant for the central nervous system. It keeps us awake by blocking one of the body's sleep-inducing molecules, called adenosine.

Your body gets its supply of energy by breaking down ATP, a high-energy molecule. In the process, adenosine is released. When adenosine docks at the receptors in your brain,  it activates a cascade of biochemical reactions that makes your neurons fire more slowly, making you get sleepy.

Caffeine interfears with this process of slowing your neurons.

Adenosine receptors are linked to the dopamine receptors in some neurons in the brain.

Dopamine promotes feelings of pleasure. When adenosine docks in one of these paired receptors, it makes it harder for dopamine to fit in its own place and interrupt mood-lifting.

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