Regular coffee drinkers don’t get a pick-me-up from their morning cup of coffee, British scientists say, attributing this to a tolerance to both the anxiety-producing and stimulating effects of caffeine. As a result, regular coffee drinkers are only brought back to their regular level of alertness. In the study, 379 adults, half of them non-to-low caffeine consumers and the other half medium-to-high consumers, were asked to give up caffeine for 16 hours. Instead, they were given either caffeine or a placebo. They were then asked to rate levels of anxiety, alertness and headache. Medium-to-high caffeine consumers who got the placebo noted a decrease in alertness and increased headache, which wasn’t reported by those who got caffeine. However, post-caffeine levels of alertness weren’t any higher than non-to-low consumers who got a placebo.