It depends too on the type of coffee you drink. It sounds like it should be opposite but the lighter/milder the roast the more caffeine you are consuming. The darkest of roasts have considerably less caffeine (incidentally it takes about 3 shots of espresso to equal the caffeine in a standard mug of mild roast coffee).

I drink light roast in the morning. I believe I do wake up quicker and consequently more energetic with that first hit of caffeine. I drink coffee throughout the day switching in the afternoon to a darker roast. I avoid decaf altogether.

FYI, the same is true for the acidity level; the lighter the roast the heavier the acid content. Thus, if you have problems with acid, switch to a much darker roast.

On a related note, my psychiatrist has suggested I added high fat dairy to my coffee. Apparently dair fats are very good for brain health.