If you’re anything like me, and the estimated 62% of Americans who drink coffee daily, you not only love the taste—you love the way your cup of joe makes you feel. From the increased focus to the mood boost, coffee’s simply the best.
Caffeine (the world’s most widely-used psychoactive drug) is a stimulant found in coffee, tea, soda, and chocolate. It can also be hiding in some medications and supplements, particularly weight control products. And, of course, in energy drinks, which can contain excessive amounts of caffeine.
According to the U.S. Food and Drug Administration, caffeine is generally safe in moderate amounts (under 400 milligrams daily) for healthy adults. Coffee, which is how the majority of us get our daily dose, typically contains 80 to 100 milligrams of caffeine per cup. A stronger brew will naturally contain more. Meanwhile, there’s anywhere from 40 to 250 milligrams of caffeine per 8 ounces in energy drinks.
Energy drinks also contain plant-based chemicals that have a stimulatory effect or build upon the available caffeine in the beverage, says James Giordano, Ph.D., a professor in the department of neurology and biochemistry at Georgetown University Medical Center, who warns against mixing coffee with other stimulants.
How does too much caffeine increase stress?
Once caffeine is absorbed in the bloodstream, it passes up to the brain where it blocks chemicals known as adenosines, which cause drowsiness. This increases activity in the brain that stimulates your central nervous system, activating your body’s stress response.
The result is a cascade of chemical reactions, including the release of adrenaline and cortisol (the stress hormone), that prepare your body for “fight or flight.” Not only do you feel more alert, your heart also beats faster, blood flow increases, and muscles tense—all of which can be helpful in small doses.
“Imagine muscles that are being prepped for sudden exertion but there’s nowhere to go. This translates into what we know as the jitters,” she explains. The increased blood flow and heart contractions can even lead to palpitations, which can feel like a panic attack.
It’s like adding fuel to the fire, according to Lina Begdache, Ph.D., a nutrition scientist and assistant professor of health and wellness studies at Binghamton University. “In small amounts caffeine can actually boost your mood,” she says. But if you exceed certain levels, it will increase (and prolong) the stress response past the point of being helpful.