Study finds regular drinkers need it simply to return to normal state of alertness
WEDNESDAY, June 2 (HealthDay News) -- If you shudder at the thought of having to start the day without a cup of coffee, new research hints at why you may feel this way.
Regular coffee drinkers seem to need caffeine to return to their normal state of alertness and to avoid the side effects of caffeine withdrawal such as headaches. That runs counter to popular belief that drinking caffeinated beverages offers some added boost in alertness, the researchers said.
"Although caffeine consumers feel alerted by caffeine, the effect is actually only bringing you back from caffeine withdrawal-induced, low-level alertness," said study author Peter Rogers, a professor in the department of experimental psychology at the University of Bristol in England. "You are not gaining anything over and above a non-consumer of caffeine."
The study is published online June 2 in the journal Neuropsychopharmacology.
Caffeine, sometimes called the most commonly used drug in the world, acts on the central nervous system's receptors for the neurotransmitter adenosine, according to background information in the study. Adenosine is involved in regulating blood pressure, as well as sleepiness and wakefulness, alertness and anxiety responses, Rogers said.
In the study, researchers asked 379 participants to abstain from drinking caffeinated beverages for 16 hours. They then gave half of the participants 100 milligrams of caffeine (the equivalent of one to two cups of coffee), and another 150 milligrams of caffeine an hour and a half later. The other half were given a placebo.
Participants were also asked about their normal consumption of caffeinated beverages. Light caffeine consumers were those who drank less than 40 milligrams a day, or less than the amount of caffeine found in one cup of coffee. A cup of instant coffee has abo
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