Definition: Caffeine is a naturally occurring chemical that has stimulant and mild diuretic (increasing urination) properties. It is a bitter alkaloid that acts on the central nervous system to increase alertness and vigilance, as well as to extend wakefulness.
This is accomplished by binding certain receptors in the brain, which inhibits the sleep-promoting actions that normally increase with prolonged wakefulness.
Caffeine is found in coffee beans, tea leaves, cocoa beans, and kola nuts and is commonly added to soft drinks, foods, and medications.
Examples:
Caffeine helps me stay awake when I don't get enough sleep.
