BBC News: Coffee ‘no boost in the morning’.
That morning latte or espresso may not be the pick-me-up people think it is, a study has revealed. University of Bristol researchers say the caffeine eases withdrawal symptoms which build up overnight, but does not make people more alert than normal. The work, presented to the British Nutrition Foundation conference, showed only people who have avoided coffee for a while will get a buzz from caffeine. But the British Coffee Association said regular drinkers did feel more alert.
The article says the morning jolt is just a perceived buzz bringing you up to normal levels of alertness. I’m sticking with my caffeine-free rooibos tea, but grapefruit juice first thing seems to have a wake-up effect on me.