Maybe they should think about how much caffeine they put in energy drink just because the Mayo Clinic stated that consuming more than 500-600 mg of caffeine a day may lead to insomnia nervousness, restlessness, irritability, an upset stomach, a fast heartbeat and even muscle tremors. Previous research has linked even moderate amounts of caffeine to negative health effects. The way caffeine affects your body is caffeine can also metabolize at different rates among individuals for various reason. Caffeine is ok if you drink it occasionally but for you to drink them everyday that might be a problem because those numbers add up quickly and you would not even know it just because you do not watch what you drink. Caffeine is a central nervous system (CNS) stimulant of methylxanthine class. It is the worlds most widely consumed psychoactive drug. Unlike many other psychoactive substances, it is legal and unregulated in nearly all parts of the world. Caffeine has a number of impacts on the brain, not only increasing production of dopamine and adrenaline (to an extent – resulting in the bobbing legs and fluttering heart), but also blocking our adenosine receptors. Adenosine is a substance that build up in the brain throughout the day and ultimately makes us feel tired and lethargic when it interacts with out adenosine