Those of us for whom a takeaway cup of the dark stuff provides the spark to get us going in the morning may greet this finding with scepticism – so how was this conclusion arrived at?

Researchers from the UK’s University of Bristol carried out tests on 379 study subjects who abstained from caffeine for 16 hours prior to being given either caffeine or a placebo. The results showed no significant variation in alertness levels.

The team, led by Peter Rogers from the university's Department of Experimental Psychology, found that regular coffee drinkers develop a tolerance to both the perceived pro’s and cons of coffee; namely, its anxiety-producing and its stimulatory effects.

So, how to explain the dependence many frequent consumers have on this humble refreshment? The research suggests that the feelings of alertness are actually just the reversal of the fatiguing effects brought about by acute caffeine withdrawal. This conclusion, coupled with previous findings linking caffeine to anxiety and raised blood pressure, would suggest that we ought to be knocking the morning cappuccino on the head.

Rogers said, ‘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.’

Source: University of Bristol & Neuropsychopharmacology