Too much caffeine, whether from coffee, tea, or energy drink, can ruin your day. Here's why your daily jolt makes you jittery, and what you can do to get rid of an unwanted buzz.

How Much Is Too Much?

First, a technical question: How much caffeine is too much? From a regulatory standpoint, answering this question has proved next to impossible. The crux of the issue is that caffeine toxicity varies according to how quickly your body processes the molecule. Now, a spherical human of average mass, metabolism, hormonal makeup and liver function requires about five hours to break down 50% of the caffeine in its bloodstream. But you are not a uniform sphere. Maybe you're six years old. Or maybe you're a woman on birth control. Or you're a man. A tall man. And you smoke a pack a day. The point is, everyone processes caffeine differently – at times, dramatically so. Metabolism, medical history, gender, medications (like birth control), genetics, even whether a person is a smoker, can play a role in a person's caffeine sensitivity. What one person's body metabolizes in two hours, another person's might process in six.

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Considerations like these have made setting a catch-all "safety limit" for caffeine surprisingly difficult. In fact, regulatory bodies like the FDA have stopped short of doing so. There's some general agreement that pregnant women should consume less caffeine than they normally would, and that kids should have even less than that – but a general consumption cap for healthy adults has proved elusive. In the end, we know that the caffeine content in something like five ounces of coffee isn't going to kill you, but that five gallons probably will.

Why Are You Jittery – And How Do You Make It Stop?

But then, if you're like me, you don't need the FDA to tell you when you've had too much caffeine. Like most habitual coffee drinkers, I know overcaffeination when I feel it. When I have a cup of coffee too late in the day, I can have problems getting to sleep. If I drink too much in one sitting, my body lets me know. I get edgy. Jittery. Occasionally, it leaves me feeling ill. Just a few sips too many, and I turn into a tightly wound, tachycardic, vaguely nauseous ball of stress.

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According to Duke University researcher James Lane, this is to be expected. "Think of caffeine as a drug that creates 'stress,' and has similar effects on the body," says Lane, who, as a professor of psychiatry and behavioral sciences, has spent years researching caffeine's effects on the mind and body. Like stress, caffeine boosts your body's adrenaline levels, which produces symptoms like high blood pressure, sweatiness, jittery sensations, and a host of other symptoms we associate with overcaffeination.

These effects, says Lane, are far-reaching. Caffeine inhibits the effects of a regulatory molecule called adenosine. In a healthy person, adenosine circulates throughout the body keeping organs like your heart and lungs in check, and plays a particularly important role in the nervous system. When caffeine blocks the action of adenosine, says Lane, things can get "out of whack":

My early studies showed that caffeine exaggerated the stress responses that were produced by threatening challenges in the task, like performing arithmetic in your head as fast as possible. I think that caffeine always exaggerates the effects of whatever stresses we are currently experiencing in everyday life. It is curious that people often turn to coffee in times of stress, like deadline pressure. The caffeine makes the deadline more stressful.

This leaves me wondering: Are there any tricks people can use to get rid of these stressful side effects more quickly than if they were to just wait it out?

In the past, I've been told to eat bananas or drink a lot of water – but NPR recently debunked the former, and the latter, like most advice on the matter that I've encountered online, strikes me as pretty dubious. On a recent visit to Stumptown coffee roasters in Portland, Oregon, a tour guide told me the only way to get coffee out of your system faster is to exercise, because it "helps you metabolize it faster."

Lane tells me that, to the best of his knowledge, there hasn't been any research on how to get rid of caffeine jitters, though he agrees that bananas probably won't help. "Potassium levels are not the issue," he says. Chugging water probably isn't the solution, either. "Water consumption won't speed up the liver's breakdown of the molecule," he notes.

Exercise, however – now that, Lane says, might actually work. "Adrenaline, the hormone responsible for the fight-or-flight response, is released during stress to prepare the body for intense activity," he says. "Maybe, the intense activity of physical exercise would relieve the effects of the higher adrenaline after too much caffeine," he muses – and "that could possibly relieve the jitters." (He does say, however, that my tour guide was wrong about exercise leading to faster caffeine breakdown.)

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Unfortunately, says Lane, apart from exercise, your options for flushing your body of a bad buzz are probably limited to riding it out.

Something to keep in mind, says Lane, is that "most of the questions people have about caffeine have never been addressed by scientific studies." What studies have been done have been performed on animal models. But mice and rats metabolize caffeine a lot faster than humans, which makes it difficult to compare health effects between rodents and people.

Given the popularity of caffeine, (it is, by far, the most widely consumed psychoactive drug on Earth), perhaps it deserves more attention.