'People become immune to coffee boost', experts believe

Using coffee for a pick-me-up may be pointless if you drink it all the time, researchers believe.

Experts say they have discovered that people who drink a lot of caffeine develop a tolerance to its stimulatory effects.

While caffeine can give people a buzz, raising alertness, the effect only works in those unused to the drink, they tell Neuropsychopharmacology journal.

They base their assumptions on the results of an experiment that they carried out on 379 volunteers.

Cold turkey

To put coffee to the test, the scientists from the UK and Germany asked all of the trial participants to abstain from the beverage for 16 hours.