Study Provides a Wake-Up Call for Coffee Drinkers

(June 3) -- If you think you're going to get a kick-start to your day by drinking a cup or two of coffee, it might be time to think again.

A study has found that the bounce that frequent coffee drinkers feel is actually the reversal of acute caffeine withdrawal, not something that's bringing the brain up to super-speed.

"Our study shows that we don't gain an advantage from caffeine," according to Peter Rogers, a lead author of the study by Bristol University's Department of Experimental Psychology in the U.K.

"Although we feel alerted by it, this is caffeine just bringing us back to normal," he said. "On the other hand, while caffeine can increase anxiety, tolerance means that for most caffeine consumers this effect is negligible."

To study possible genetic differences, blood samples were taken from 379 volunteers who agreed to stop drinking coffee for 16 hours. After that, they were given either a placebo or caffeine.

They were later given a slightly higher dose of caffeine or another placebo, followed by psychological tests to measure their emotional state and range of alertness.

Results published in the magazine Neuropsychopharmacology showed that caffeine did not increase the alertness of any of the groups, which ranged from about half who were high or medium caffeine consumers to those who usually drank little or no coffee at all.

Those who described themselves as medium and high caffeine users who took the placebo reported a decrease in alertness and an increase in headaches, which did not show up at all in those who were given coffee.

However, according to the study's results, the post-caffeine levels of alertness were no higher than the levels for those who took the placebo, suggesting caffeine only brings coffee drinkers "back to normal."

The alertness levels were measured by getting the volunteers to carry out computer tests, which also revealed their levels of memory, attentiveness and vigilance, The Times of London reported.

People with a genetic disposition to anxiety tended to consume slightly larger amounts of coffee, suggesting that a mild increase in anxiety might be part of the caffeine buzz, the researchers concluded.

The research is significant, The Guardian of London reported, because previous studies involved far fewer people.

"Someone who consumes caffeine regularly when they're at work but not at weekends runs the risk of feeling a bit rubbish by Sunday," Rogers told The Guardian. "It's better to stick with it or keep off it altogether."