I cut caffeine out of my life completely when I went to see a psychiatrist about my anxiety problems and she told me one cup of coffee was enough to trigger a panic attack. A year later and I still don't consume it. I sleep better, go to bed and wake up on time, and have much more manageable energy levels throughout the day.

Just because it's socially accepted doesn't mean it isn't one hell of a drug.

(If you want a citation for caffeine's anxiogenic effects: http://ajp.psychiatryonline.org/cgi/content/abstract/145/5/6...)