Key finding: "Although frequent consumers feel alerted by caffeine, especially by their morning tea, coffee or other caffeine-containing drink, evidence suggest

Key finding: "Although frequent consumers feel alerted by caffeine, especially by their morning tea, coffee or other caffeine-containing drink, evidence suggests that this is actually merely the reversal of the fatiguing effects of acute caffeine withdrawal," said Professor Peter Rogers, of Bristol University, and colleagues. So lets say if your baseline alertness when you never drank coffee was 5, drinking coffee will temporarily boost it to 7, but if you keep drinking coffee, the tolerance will make it so that your baseline will eventually fall to 3 and you need coffee to temporarily boost it back to 5.