MILLIONS of people all over the world can’t face the day without a cup, but the benefits of coffee have been overstated. New research has found that caffeine has no stimulating effect on the brain and does not counteract sleepiness.

It suggests drinkers who believe coffee provides a morning boost and makes them more alert are reversing withdrawal symptoms they have developed overnight through dependence on the substance.

Jack James and Michael Keane of the psychology department at the National University of Ireland, Galway (NUIG), examined the effects of coffee by studying electrical activity in the brain. They say the findings call into question road safety policies that urge tired drivers to drink two cups of coffee to ensure alertness at the wheel.

James said: “Caffeine is supposed to have an arousing effect on the central nervous system, including the brain, allowing us to take on difficult tasks more effectively and to perform at a higher level more generally. It is also purported to be able to reverse the dulling effects of lost sleep. But we found that caffeine had no net benefits. The effects are all explained by reversing the withdrawal that caffeine usage causes in the first place.”

Most Irish adults consume between two and five cups of coffee or tea a day. One cup of tea usually contains about half to two-thirds the amount of caffeine of a cup of instant coffee. A shot of fresh coffee contains even more caffeine.

Caffeine that has been consumed during the day is eliminated from the system at night, so by morning the body is in the early stages of caffeine withdrawal. “If you consume caffeine daily you become physically dependent, you experience withdrawal and the withdrawal can be removed by taking caffeine again,” said James.

The stimulating effects of coffee have been widely promoted. On its Irish website, Aldi claims: “Caffeine makes the tired lively, awakens the spirit, energises the metabolism, and increases concentration, ability and attention. Passionate coffee drinkers are convinced coffee accelerates the thought process — that’s why they gladly call it the ‘think drink’.”

Previous research showed caffeine boosted performance, but had not taken into account that caffeine usage produces physical dependence, and the large majority of participants were habitual consumers who were coming into the laboratory in the early stages of withdrawal, according to James.

The Galway study, published in the journal Human Psycho-pharmacology, used the same set of subjects for at least a month. They were given either a placebo or measured amounts of caffeine in capsule form (equivalent to about one cup of coffee) three times daily. They were than asked to perform a task which tested their ability to concentrate.

“We had participants off caffeine for a sufficiently long period that they were no longer physically dependent on it, and therefore withdrawal was not an issue,” said James. “They were back to how they would be functioning if they were never a caffeine consumer. We find when we give them caffeine at that point you get no effect.The only time you see an effect is when the person has been using the compound daily for long enough to develop physical dependence.”

The participants had their sleep restricted to 40% of normal on some nights. “They were groggy the following day and it was a good test of whether caffeine provides a pick-me-up when you’re sleepy,” said James. “If you are sleepy and you are caffeine deprived, it will reverse the effects of the caffeine deprivation, but it doesn’t do anything at all in relation to the sleep loss.

“This feeds directly into public policy, which is that people who are driving should pull over and have a couple of strong cups of coffee and a nap. If we were serious about reducing road fatalities as a result of sleep deprivation and tiredness caused by caffeine withdrawal, we should be advising people not to be caffeine consumers in the first place.”

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