I've noticed when I consume caffeine, and this seems to be dependent on my hormone or cortisol levels, but I have immediate vasoconstriction in my forearms and my finger tips go cold. This lasts about 30 minutes to an hour. It also seems to happen when I eat larger meals. I know cortisol can triple when you eat meals, larger ones. It seems that the cortisol release is over responsive in these situations, and thus while my normal cortisol levels may be normal or low normal, any form of stress causes a hyper response, and too much gets released. Does anyone else have this happen?