Had problems with this myself and it turned out the coffee was part of the problem, not the solution. [In a very roundabout way.] Let's just say that sleep disorders can play heck on your libido, and when the coffee is contributing to that underlying issue, then it's not doing you any favors. It's all about balance and being aware of your body.

I also learned about a bevy of different foods that can have an effect. Read all about lifestyle changes and other things you can do before you resort to taking drugs for the problem when I was doing my research.