Most of the caffeine we consume is found in coffee and tea, but it can also be found in some sodas, chocolate, caffeine pills, and decaf beverages.

Caffein helps us feel alert, focused, happy, and energetic, even if we lack sleep. However, it can also raise our blood pressure and make us feel anxious.

Caffeine is found the leaves and seeds of certain plant species. It's toxic to insects, but when they consume it in lower doses, such as found in nectar, it can help them to remember and revisit flowers.

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.