Once again, this is one of those "huh?" articles since a study focusing on coffee was done no less by Brits. Given the reality that Brits are known for their love of tea, it's sort-of - well -weird that they are involved in this type of research. Actually, and at least for me, the results are somewhat confusing.
Researchers working out of Bristol University found that drinkers develop a tolerance to anxiety-producing and stimulating effects of caffeine.
Uh - duh! This is not news, people!
Then the report goes on that caffeine only brings people back to baseline levels of alertness - not above them. Whatever that means...
According to researcher/scientist, Peter Rogers of Bristol's dept. of experimental psychology(!), although heavier coffee drinkers feel that morning caffeine high, evidence suggests that it's actually the opposite and instead they experience withdrawal and fatigue. So if we understand this correctly and it's not easy, that first morning caffeine upper so-to-speak, really is a downer and the reason for morning fatigue.
More information we perhaps may-but-not-necessarily need.
"The authors also found that the genetic predisposition to anxiety did not deter coffee drinking. In fact, people with the gene variant associated with anxiety tended to consume slightly larger amounts of coffee than those without the variant, suggesting that a mild increase in anxiety may be a part of the pleasant buzz caused by caffeine."
This could mean that people who come from families with somewhat nervous personalities or dispositions, enjoy coffee. At least this is my interpretation.
Anyway, more background info. can be found here: http://www.sciencedaily.com/releases/2010/06/100602211940.htm
As a tea drinker, mainly, but a coffee enjoyer too, my first morning cup of tea and/or coffee is a necessity in spite of these - well - convoluted findings. There is nothing like the sensation of the hot tea/coffee liquid as it hits the stomach, circulates around the body and finally makes it to the brain. Right?