It’s important to remember when you’re sipping the first morning cup that caffeine is a stimulant, which increases the speed that messages are communicated to and from the brain.

Caffeine is commonly found in coffee, many teas, sodas, energy drinks, chocolate, energy bars, and weight-loss pills or powders. In fact, caffeine is the most commonly used drug in the United States and is consumed by 90 percent of Americans, with half of them consuming more than 300 milligrams (or about three cups of coffee) per day.

Physical effects of caffeine

The stimulant effects of