Venti

Science World, Feb 7, 2005 by Jacqueline Adams

Banish your venti-sized coffee cup. Harvard scientists have found that ingesting tiny doses of caffeine (chemical found in coffee) throughout the day keeps you more alert than having one huge, a.m. java jolt.

Why? Consider how caffeine works: As you burn energy to perform daily activities, your body cells produce adenosine. This chemical binds to special receptors on the cell surface, signaling you to feel sleepy. Caffeine tricks your body into feeling alert because its molecules (particles of two or more atoms, the smallest units of an element, joined together) are similar in structure to adenosine molecules. They fit into the cell receptors, too. With caffeine in the way, adenosine can't deliver its need-for-sleep message.

But caffeine exits the bloodstream as the day progresses. So the jolt you get from a giant morning coffee dwindles fast. Instead, participants in the Harvard study ingested a small dose of caffeine every hour, with the equivalent of one eight-ounce coffee lasting a person an entire day. The result: constant pick-me-ups throughout the day.

This dosage strategy may help people like firefighters, who need to stay awake during emergencies. But Tom Scammell, a neurologist (brain scientist) at Harvard, warns that it isn't a sleep substitute. "Not sleeping is like not paying off a loan. The debt is still there, and the amount of sleep you owe keeps growing."

Charles Czeisler, a biologist who worked on the study, adds that cheating on sleep spells big trouble for teens. Teens need 9 to 10 hours of sleep per day for healthy development. If you feel tired, Czeisler says, your body is telling you to hit the pillow--not the caffeine.

Did You Know?

* In huge doses, caffeine is lethal. Scientists calculated the deadly dose at more than 10 grams. That's equivalent to drinking 80 to 100 cups of coffee in one sitting.

* Believe it or not, coffee is second to oil as the most-valuable commodity in the world. The United States imports approximately one sixth of the world's yearly crop.

* Finland is home to the world's record coffee drinkers. The average Finn drinks approximately 1,400 cups per year.

Resources

* Learn more about the Harvard Medical School caffeine-dosage study at: www.news.harvard.edulgazettel20041 05.13/12-caffeine.html

* For great information on caffeine, check out the Center for Science in the Public Interest's Caffeine: The Inside Scoop: www.cspinet.org/nah/caffeine.htm