Yes, lighter brewed coffee's pack more of a caffeine punch!
Did you know that the roast of the bean does not determine the caffeine content?
As a matter of fact, if you are visiting your local Starbucks for the caffeine boost, you might want to give their lightest 'blonde' roast a try. It packs the caffeine punch! Surprised?
The degree of the roast misunderstood because it goes against what your eyes and brain are telling you should be true.
The different origination of the coffee bean will give you a vast difference in the flavor to start. Ethiopian, Guatemalan, Indonesian, African...they all have their own regional flavors but they are similar in the roasting process to start with.
If the are roasted to a medium roast, the acidity will decrease, a bit of fullness added the bitterness is balanced.
When the bean is continued to be roast, it obviously gets darker. But with that, the distinction between regions is less pronounced and the roasting itself begins to impart more of itself on the bean. This means the coffee will not only be darker, but more bitter and fuller. Along with the longer roasting time and darker color, caffeine levels drop.
The roaster used and the person doing the roasting has a rather large impact on the final flavor of the brew as well. While I used to think a dark roast was best, and the lighter roasts were merely colored water, I came to realize as I gained information and experience that the lighter roasts not only had higher caffeine content, but you could taste the subtle differences in flavor so much better as well as the under tones that are gone by the time the bean is roasted dark.