This article mentions nothing about how they measure alertness. How objectively can this possibly be measured? It seems to me that the measure of alertness may

This article mentions nothing about how they measure alertness. How objectively can this possibly be measured? It seems to me that the measure of alertness may only be indirectly measured in by task specific performance. So there may be driving alertness, data-entry alertness etc... On the other hand, even if all the chemical effects are quantifiable, so the measure is "objective", does that really mean anything for different individuals? Also, for a given task, it may turn out that I need the anxiety producing effects of caffeine just to care enough to perform the drudgery. Whew! Time for a second cup.