The researchers asked the volunteers to abstain from consuming any caffeine for 16 hours and then gave them either caffeine or a placebo. Each participant then rated their levels of anxiety, alertness and whether they got a headache.
Those who consumed medium to high amounts of caffeine reported they were less alert and more likely to get a headache when they took the placebo but not when they got their caffeine fix, the researchers report in the journal Neuropsychopharmacology.
Those who got caffeine reported levels of alertness that were no higher than those who typically don’t get much caffeine who received a placebo. That suggests that caffeine only brings coffee drinkers back up to their normal state, probably because they develop a tolerance for its effects over time.
Thursday, June 3, 2010
From a study conducted of 379 volunteers in England.