The most common sources of caffeine for human consumption are the tea leaves of the Camellia sinensis plant and the coffee bean, the seed of the Coffea plant. Some people drink beverages …

If you have problems with your PC locking or going to sleep, caffeine will keep it awake. It works by simulating a keypress once every 59 seconds, so your machine thinks you're still working at the …

Feb 21, 2025 · Up to 400 milligrams (mg) of caffeine a day seems safe for most adults. That's about the amount of caffeine in four cups of brewed coffee, 10 cans of cola or two "energy shot" drinks. Keep …

Mar 21, 2025 · What is caffeine? Caffeine is a type of drug called a stimulant, meaning it increases chemicals in your brain called neurotransmitters.

Jun 3, 2020 · Caffeine is a natural stimulant consumed throughout the world. This article reviews caffeine and its health effects, both good and bad.

Caffeine is a natural chemical with stimulant effects. It is found in coffee, tea, cola, cocoa, guarana, yerba mate, and over 60 other products. Caffeine works by stimulating the central...

Although we tend to associate caffeine most often with coffee or tea, the research below focuses mainly on the health effects of caffeine itself. Visit our features on coffee, tea, and energy drinks for more …

Apr 1, 2024 · While caffeine consumption is generally safe, this review paper also examines the potential effects that caffeine could have on human health and development.

Caffeine is a trimethylxanthine in which the three methyl groups are located at positions 1, 3, and 7. A purine alkaloid that occurs naturally in tea and coffee.

Feb 23, 2026 · Learn how caffeine affects brain chemicals and health, sleep, and mood. Understand safe daily limits, hidden sources, and signs you’re getting too much.