For 12 years I worked as a barista. Believe me, caffeine is a powerful drug. Myself, I love espresso and drank it with no problem for well over a decade. All of a sudden I began having severe anxiety issues when I drank espresso or ANY caffeine (and that definitely includes green tea). I stopped all the caffeine for a couple of years. Now I can drink a little bit of espresso or coffee, but I almost always do all or half-caf. Caffeine is like that...you can do fine with it for years, then one day your body just cannot tolerate it anymore.