Prime Your Gray Cells

Wiring your brain for happiness and success

Does Coffee Perk Up Your Brain . . . or Not?

Coffee: Not quite the wake-up drug you think it is

Coffee may be the most popular drug in America; some 85 percent of Americans confess to drinking coffee daily. We love our coffee because its high caffeine content serves as a relatively fast-acting stimulant. So what if it temporarily increases your heart rate and blood pressure? It wakes us up, helps us focus, and boosts the production of serotonin receptors in our brains, which contributes to the feelings of mood enhancement from a good cup of coffee. Sure, too much can leave you jittery and nervous, and too much can prematurely age your brain because it dehydrates and reduces blood flow, but it tastes sooooo good, creating a debate that goes on and on: How much coffee is too much coffee?

Are You Hearing Things?

According to a small study recently published in the journal Personality and Individual Differences, Australian researchers recently found that drinking five regular cups of caffeinated coffee may raise the risk of auditory hallucinations. LaTrobe University researchers asked ninety-two people with varying levels of caffeine intake-and stress-to listen to three minutes of white noise via headphones. The researchers told the study participants that Bing Crosby's rendition of "White Christmas" would be played in the headphones and instructed them to push a buzzer when they were able to hear the song.

Well, the researchers never actually played the song, but study participants pushed that buzzer anyway. Those who drank five or more cups of coffee buzzed three times on average, while the participants who drank less coffee buzzed just once. Another study published in 2009, in the same journal, showed that people who consumed the equivalent of three brewed cups of coffee were three times more likely to hear or see things that weren't there.

These studies theorized that caffeine (in coffee, and other foods, drinks, and drugs) may worsen the effects of stress on the body by increasing the amount of cortisol your body releases when under duress. So if you go for that third cup of coffee each morning, are you likely to see or hear visions? If you took these studies at face value, perhaps you'd have reason to be a tad worried. We, personally, would like to see additional, more nuanced studies before we accept that a mere five cups of coffee a day can produce hallucinations for people who are under exceptional stress, or anyone else.

However, if you love coffee-and we do-you probably justify excessive consumption by saying, and perhaps believing, that it fires up your brain, making you more productive and, well, smarter. You think coffee is the perfect pick-me-up drug . . . but is it?

Not Quite the Wake-Up Drug You Think It Is

Downing those cups of coffee in the morning may fire up your neurons, but studies show that caffeine only increases the output and quality of your work if the work you're doing doesn't require nuanced or abstract thinking. Caffeine seems to speed your thinking processes up a bit, and improve memory creation and retention when it comes to declarative memory, the kind you use when memorizing lists. It doesn't seem to help at all when it comes to creative energy, or to thinking beyond basic tasks. Thanks to the increasing tolerance that comes with regular consumption, it eventually takes more and more caffeine to get the same effect.

It's also true that consuming too much caffeine can irritate your stomach, cause headaches, create anxiety, serve as a diuretic, and disturb your sleep. And it's important to note that caffeine is not only found in coffee beans but also in tealeaves, cocoa beans, and in products derived from these sources. Further, you may not be aware that caffeine is also found in more than a thousand different over-the-counter and prescription drugs and vitamin supplements and that there is a very small amount of caffeine in decaffeinated coffee.

So How Much Is Too Much?

As long as you still drink plenty of healthy beverages, such as water, fruit juice, and milk, you can have a few cups of coffee and feel perfectly good about it. Most coffee mugs, however, actually contain two to two and half cups, and the fancy sizes at your favorite coffee places can hold a lot more coffee (and caffeine) than you think. The pharmacological active dose of caffeine is defined as 200 milligrams, and the daily-recommended not-to-exceed intake level is the equivalent of one to three cups of coffee per day (139 to 417 milligrams). Doctors say 600 mg a day of caffeine can cause anxiety, difficulty breathing, and an irregular heartbeat.

Below is a guideline for approximate amounts of caffeine in commonly used foods and beverages:

§         Coffee, brewed from ground beans: 6 ounces  = 100 milligrams

§         Tea, brewed from whole leaves: 6 ounces = 10-50 milligrams

§         Cola, can or bottle: 12 ounces = 50 milligrams

§         Cocoa, as milk chocolate bar: 1 ounce  = 6 milligrams

§         Semisweet chocolate chips: 1 cup= 92 milligrams

The Cold Hard Facts

Caffeine is not stored in the body, so its effects are not permanent. Its impact can start to be felt ten to fifteen minutes after ingestion, and the effect lasts two to three hours. People who regularly consume more than 300 milligrams a day may suffer withdrawal symptoms if they abruptly stop. These symptoms include fatigue, depression, irritability, jitters, and headaches as blood vessels in the brain dilate. To ease symptoms, cut back on other caffeine sources, such as tea or soda, and drink coffee that is half caffeinated and half decaffeinated. If you pare back slowly over the course of a few weeks, your transition will go more smoothly-and your headaches will disappear in a week or two; after which, you can elect to consume an amount of caffiene that provides the goodies you love but doesn't lead to negative effects.

Can You Overdose?

A man in England actually died from a caffeine overdose. He had purchased caffeine powder over the Internet, and didn't heed the instructions to never take more than 1/16th of teaspoon. According to reports, he swallowed one or two teaspoons of the highly concentrated powder. You're not likely to make the same mistake, but it is important to know that there is such a thing as caffeine overdose.

Mixing alcohol and caffeine is a very bad idea. In November, 2010, the Federal Trade Commission (FTC) issued a strong warning that caffeinated alcoholic beverages posed a "significant risk" to consumer health and that inexperienced drinkers "may not realize how much alcohol they have consumed because caffeine can mask the sense of intoxication."

The Food and Drug Administration (FDA) consulted experts in toxicology, neuropharmacology, emergency medicine, and epidemiology to contest beverage manufacturer claims that the addition of caffeine to alcoholic beverages was "generally recognized as safe." They also deemed that the beverages "posed a public health concern." Most of those beverages have removed the caffeine, but it's wise to read labels carefully and steer clear of alcoholic beverages that include caffeine.

Does Drinking Coffee Sober You Up?

In movies we often see characters drinking coffee after a binge, but research has found the caffeine in coffee (or in alcoholic drinks) doesn't have a sobering effect. In fact, it seems only to make drunk people think they're sobering up. Studies have found that people who drink caffeine along with alcohol think they're sober enough to drive, but the truth is that their reaction time and judgment remain impaired. College kids who drink both alcohol and caffeine were found more likely to have car accidents. [Some studies point to exercise as the quickest way to sober up when drunk.]

It Will Affect Your Sleep

All types of caffeine affect your ability to fall asleep and stay asleep. Coffee is the most well known offender, but remember that caffeine can also be found in tea (both black and green), cola, chocolate, and decaffeinated coffee. Other sources of hidden caffeine are pain pills, weight-loss pills, diuretics, vitamin supplements, and cold medicine, all of which may have enough caffeine to equal one cup of coffee.

Don't Toss Out the Coffee Quite Yet


Our brains have a thin coating that separates it from the rest of the body called the "blood-brain barrier." This vital coating can become susceptible to damage from disease and stress, and researchers have recently found some evidence that the caffeine in coffee products may actually help to protect the coating and repair the damage, as well as ward off other harmful invaders. So score one for the cup of java-just don't take this news as permission to drink too much caffeine every day!

Teresa Aubele, Ph.D., is a coauthor of Train Your Brain to Get Happy. She conducts neuroscientific research at Florida State University.

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