
For all of its wild popularity, caffeine is one seriously misunderstood substance. It's not a simple upper, and it works differently on different people with different tolerances—even in different menstrual cycles. But you can make it work better for you.
-Lifehacker.com
Check out What Caffeine Actually Does To Your Brain over at Lifehacker. It is well worth the read if you are interested in the science behind your caffeinated mornings.