Excessive intake of coffee can seriously deplete INOSITOL --- do some searches on coffee - inositol. Inositol & choline are necessary for brain function, and Acetyl L-Carnitine, first thing in the morning on an empty stomach can increase energy & concentration without the jittery anxious feelings occasionally associated with coffee/caffeine or even with the amino acid tyrosine.

There's lots of info at google for the depletion of inositol by too many daily cups of coffee.