9781422288047

Caffeine is a kind of drug called a stimulant. Stimu- lants speed up your nervous system. They make you feel excited and alert and full of energy. This sounds like a good thing—but stimulants can be dangerous.

Caffeine is also a psychoac- tive drug. This means that it’s a chemical that crosses the blood-brain barrier . It gets inside the brain and the central nervous system . It changes the way the brain works.

Caffeine is actually a chemical that’s made up of atoms of carbon, oxygen, nitrogen, and hy- drogen.

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