I like coffee, but caffeine seems to 'wire' me much more extremely than most other people. I feel energized or even shaky after less than half a normal cup, and a whole 8 ounces will usually cause me to sweat or make my heart race uncomfortably.
Even decaffeinated coffee seems to have this effect, which seems strange to me (although I am aware that it still contains a small amount of caffeine). I typically drink green tea instead of coffee, since the effect is more mild.
Is this an indication that my body metabolizes caffeine faster (or slower?) than normal? What else can cause caffeine sensitivity?