WATCH: This Is What Adderall Does To Your Brain

It's a little pill that can make you hyper-focused, suppress your appetite, and improve your mood and energy levels.

Sound familiar? Adderall is used by over 25 million people worldwide to treat ailments including ADHD, narcolepsy and depression -- and increasingly, the pills are being taken without a prescription to boost performance at school or work.

So what happens in your brain when you pop one? A new video from the American Chemical Society's series, Reactions, has some answers.

In short: It's all about the dopamine.

"People with ADHD tend to have lower levels of dopamine, the key chemical in the brain's reward center," neuroscientist Dr. Ryan Davison says in the video. "This lack of dopamine means that people are constantly seeking stimulation."

By stimulating the release of dopamine, amphetamines like Adderall keeps the brain from getting distracted by potential rewards in the environment -- from email alerts to nearby conversations to incoming text messages.

And here's a fun fact: Add four little atoms on the end of an amphetamine and you have a much more dangerous substance, methamphetamine (also known as meth). Yikes!