Healthy living * Mental wellbeing

Coffee "does not wake you up"

coffee and alertness Stimulating effect may be an illusion

A coffee hit may be what gets most of out of bed in the morning, but it seems the stimulating effect may all be in the mind - at least if you are a regular drinker, according to new research.

Nearly 400 brave souls agreed to abstain from coffee for at least 16 hours. They were then given either coffee or a placebo (fake coffee substitute) and tested for alertness. The study found little difference in the responses of the participants, regardless of whether they had taken real coffee or the substitute.

This suggests that frequent coffee drinkers develop a tolerance to both the anxiety-producing and stimulatory effects of caffeine.

In fact the stimulating effects experienced by regular coffee drinkers when they have their first drink of the day may in fact be the result of the coffee reversing the symptoms of caffeine withdrawal.

And as caffeine also tends to increase both anxiety and blood pressure, the researchers conclude that there is no real benefit to the beverage.

One of the leaders of the study, Peter Rogers, from the University of Bristol's Department of Experimental Psychology, comments: "Our study shows that we don't gain an advantage from consuming caffeine -- although we feel alerted by it, this is caffeine just bringing us back to normal. On the other hand, while caffeine can increase anxiety, tolerance means that for most caffeine consumers this effect is negligible."

The conclusions are based on the fact that in the study half of the participants were classified as either non-drinkers of coffee or low consumers, and the other half as medium/high coffee drinkers. When tested for alertness medium/high caffeine consumers who received the placebo reported a decrease in alertness and an increase in headache, neither of which were reported by those who received caffeine. But their post-caffeine levels of alertness were no higher than the non/low consumers who received a placebo, suggesting caffeine only brings coffee drinkers back up to 'normal'.

The study is published online in the journal Neuropsychopharmacology.

This article was published on Thu 3 June 2010

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