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Effects Caffeine Has on Your Reaction Times

author image Robin Elizabeth Margolis
Robin Elizabeth Margolis is a freelance writer in the Washington, D.C., area. She has been writing about health care, science, nutrition, fitness and law since 1988, and served as the editor of a health law newsletter. Margolis holds a bachelor of arts degree in biology, a master's degree in counseling and a paralegal certificate.
Effects Caffeine Has on Your Reaction Times
Three business women drinking coffee in the breakroom. Photo Credit XiXinXing/XiXinXing/Getty Images

A 2002 CBS TV broadcast jokingly referred to America as "Caffeine Nation." Americans do consume 45 million pounds of caffeine per year. That includes people who do not drink caffeinated beverages but instead ingest caffeine from other sources, such as candy and chocolate ice cream, according to a University of Washington website "Caffeine." If you ingest caffeine regularly, one reason could be because it speeds up your reaction time.

Caffeine Origins

Caffeine is found in more than 60 plants, including coffee beans, tea leaves, cacao pods and kola nuts, notes the Food and Drug Administration brochure "Medicines in My Home -- Caffeine in Your Body." Caffeine protects the plants from insects by repelling some species and paralyzing and killing others. Europeans and Americans have been ingesting coffee, tea and chocolate for centuries. In humans, caffeine operates as a central nervous system stimulant, increasing alertness and reaction times.

Reaction Time Studies

Caffeine is one of the most thoroughly studied substances in the human diet, and its effect on reaction times has been carefully verified. One example of such research is a 2010 study at the University of Western Australia in Crawley, Australia, measuring the effects of caffeine on 10 male sprinters. Caffeine ingestion improved their ability to sprint repeatedly and even improved their sprinting the day after they ingested caffeine.

Caffeine Drawbacks

A 2008 study of 270 elite Canadian athletes done by scientists at the University of Calgary, discovered that 30 percent of them ingested some caffeine every day, mostly by drinking coffee. However, none of these athletes was getting enough caffeine to enhance his athletic performance. The researchers suggested that the athletes were likely avoiding high dosages of caffeine because of the drawbacks: sleep disturbance, gastric pain, interactions with other dietary supplements and withdrawal.

Caffeine Dosage Range

A 2001 Institute of Medicine report, "Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations," discusses -- from the standpoint of the U.S. armed forces -- what might be the maximum dose of caffeine to create alertness and speed up reaction times without causing undesirable side effects. The report summarizes previous research studies as indicating that a range of 200 to 600 milligrams of caffeine would increase endurance performance and reaction times.

Determining Right Amount

One 12-ounce cup of coffee delivers 200 milligrams of caffeine. Most diet research indicates that 600 milligrams of caffeine is probably too much and likely to produce side effects, such as insomnia, headaches, irritability, irregular heartbeat and gastric problems. Still, even if you drink only one 12-ounce cup of coffee a day, you could ingest more caffeine from other sources, such as candy, tea, caffeinated soda and chocolate. You could keep a record of how much caffeine you take in each day to help track how much of this stimulant you need to increase your reaction time without triggering unwanted side effects.

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