(HealthDayNews) -- A coffee drinker finds few joys in the world comparable to waking up with that first cup.
But after that, things seems to level off. At least that's what the journal, Behavioral Pharmacology reports.
Sixty four people were given three cups of coffee each. Everybody got a first cup of caffeine; some were given caffeine all the way through; others got decaf in the second and third cup; still others got caffeine, then decaf, then caffeine.
And the results? There was no question that the first cup of real coffee brightened everybody's day. But after that, there were no real differences between the groups in terms of mood or alertness.
Apparently, caffeine has such a flat dose response that doubling or even tripling the dose doesn't increase its effect.
