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Caffeine On Assignment

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Lynne Warren

Caffeine @ National Geographic Magazine
By T. R. ReidPhotographs by Bob Sacha

Slurped in black coffee or sipped in green tea, gulped down in a soda or knocked back in a headache pill, caffeine is the world's most popular psychoactive drug.

Get a taste of what awaits you in print from this compelling excerpt.

It's hardly a coincidence that coffee and tea caught on in Europe just as the first factories were ushering in the industrial revolution. The widespread use of caffeinated drinks—replacing the ubiquitous beer—facilitated the great transformation of human economic endeavor from the farm to the factory. Boiling water to make coffee or tea helped decrease the incidence of disease among workers in crowded cities. And the caffeine in their systems kept them from falling asleep over the machinery. In a sense, caffeine is the drug that made the modern world possible. And the more modern our world gets, the more we seem to need it. Without that useful jolt of coffee—or Diet Coke or Red Bull—to get us out of bed and back to work, the 24-hour society of the developed world couldn't exist.
"For most of human existence, your pattern of sleeping and wakefulness was basically a matter of the sun and the season," explains Charles Czeisler, a neuroscientist and sleep
expert at Harvard Medical School. "When the nature of work changed from a schedule built around the sun to an indoor job timed by a clock, humans had to adapt. The widespread use of caffeinated food and drink—in combination with the invention of electric light—allowed people to cope with a work schedule set by the clock, not by daylight or the natural sleep cycle."
Czeisler, who rarely consumes any caffeine, is a bundle of wide-awake energy in his white lab coat, racing around his lab at Boston's Brigham and Women's Hospital, grabbing journal articles from the shelves and digging through charts to find the key data points. "Caffeine is what's called a wake-promoting therapeutic," he says.
Scientists have developed various theories to explain caffeine's "wake-promoting" power. The consensus today focuses on the drug's interference with adenosine, a chemical in the body that acts as a natural sleeping pill. Caffeine blocks the hypnotic effect of adenosine and keeps us from falling asleep. Since caffeine has also been shown to enhance mood and increase alertness in moderate amounts, it's a potent potion for students and scholars stuck in the lab at three in the morning. Paul Erdős, the Hungarian mathematician who often worked his equations around the clock, is known for saying that "a mathematician is a machine for turning coffee into theorems."
Caffeine's ability to murder sleep also makes it a drug of choice for long-distance travelers. There are as many different jet-lag remedies as there are seats on a trans-Pacific flight. But one approach, outlined in The Caffeine Advantage by Bennett Alan Weinberg and Bonnie K. Bealer, involves abstaining from caffeine for several days before traveling, then dosing yourself with small amounts of coffee or tea on the day you arrive to stay alert—preferably out in the sunshine—until your regular bedtime in your destination. (During weeks of global travel for this article, it worked for me.)
"Caffeine helps people try to wrest control away from the human circadian rhythm that is hardwired in all of us," says Czeisler. But then a shadow crosses the doctor's sunny face, and his tone changes sharply. "On the other hand," he says solemnly, "there is a heavy, heavy price that has been paid for all this extra wakefulness." Without adequate sleep—the conventional eight hours out of each 24 is about right—the human body will not function at its best, physically, mentally, or emotionally, the doctor says. "As a society, we are tremendously sleep deprived."
In fact, the professor goes on, there is a sort of catch-22 at the heart of the modern craving for caffeine. "The principal reason that caffeine is used around the world is to promote wakefulness," Czeisler says. "But the principal reason that people need that crutch is inadequate sleep. Think about that: We use caffeine to make up for a sleep deficit that is largely the result of using caffeine."

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Sights & Sounds
Get a buzz as photographer Bob Sacha takes you around the world to explore the international appetite for caffeine.

So you think you know everything about the highs and lows of java? Test your caffeine IQ.

What's your secret for brewing a good pot of coffee?
Flashback to 1954 when the U.S. Board of Tea Experts used a spinning table and spittoons to demonstrate tea tasting to a New York women's club president.

Do you need caffeine to function during the day? Cast your vote.

Yes     No

More to Explore

In More to Explore the National Geographic magazine team shares some of its best sources and other information. Special thanks to the Research Division.

Did You Know?
Guarana: Hidden Caffeine

Guarana is an ingredient found in many sodas, energy drinks, protein bars, and natural weight-loss aids. It comes from the seeds of a woody vine native to Brazil named for an Amazonian people, the Guarani, who process the seeds for use in food, drink, and medicine. What might be a surprise is that guarana contains concentrations of naturally occurring caffeine higher than that found in coffee, tea, cacao, and kola. Guarana sodas are immensely popular in South America, especially Brazil, and the stimulant is finding its way into more and more energy drinks. Guarana is sometimes marketed as a natural alternative to caffeine, but it's caffeine all the same. Look at the labels of some energy drinks and you'll see both caffeine and guarana, which means that you're getting caffeine from two sources.
—Heidi Schultz
Did You Know?

Related Links
National Soft Drink Association
How much caffeine is in your soda?
Caffeine and Women's Health
The International Food Information Council Foundation assesses the effects of caffeine on pregnancy, fertility, cancer, osteoporosis, and heart disease.
Mayo Clinic

Mayo Clinic staff answer food and nutrition questions, including queries about caffeine and kids, caffeine content in beverages, caffeine and blood sugar, and caffeine and weight loss.
How Coffee Works
Learn the origins of coffee drinking, how and where the beans are grown, and the science of caffeine.
Tea and Coffee Trade Journal
Although geared toward people who work in the tea and coffee industries, the features section offers articles of interest to the general public, such as "The Aromatic Coffees of India" and "The Right Mix for Herbal Tea."
PubMed from the National Library of Medicine
Search for current studies on caffeine and health. Often only abstracts are available, but they provide a good overview of the results of the studies.


Fredholm, Bertil, and others. "Actions of Caffeine in the Brain With Special Reference to Factors That Contribute to Its Widespread Use." Pharmacological Reviews (March 1999), 83-133. Available online at
MacFarlane, Alan, and Iris MacFarlane. The Empire of Tea. Overlook Press, 2004.
Maughan, R. J., and J. Griffin.  "Caffeine Ingestion and Fluid Balance: A Review." Journal of Human Nutrition and Dietetics (vol. 16, 2003), 411-20.
Pendergrast, Mark. Uncommon Grounds: The History of Coffee and How It Transformed Our World. Basic Books, 1999.
Schivelbusch, Wolfgang. Tastes of Paradise: A Social History of Spices, Stimulants, and Intoxicants. Pantheon Books, 1992.
Weinberg, Bennett Alan, and Bonnie K. Bealer. The World of Caffeine: The Science and Culture of the World's Most Popular Drug. Routledge, 2001.


NGS Resources
Zackowitz, Margaret G. "British Cool On Hot Tea." National Geographic (December 2003).

"A Tea Party for Health." National Geographic (June 2000).

"Coffee." 1999. Only available online at
Dunn, Jerry Camarillo, Jr. "Hawaii's Heady Brew." National Geographic Traveler (January/February 1991), 110-1.

Young, Gordon. "Chocolate: Food for the Gods." National Geographic (November 1984), 664-87. 
Marden, Luis. "Coffee is King in El Salvador." National Geographic (November 1944), 575-616.


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