Caffeine definitely affects me and how so depends on my underlying level of anxiety/stress, mood and medications. So, when I was dealing with chronic stress in school I pretty much found just a little caffeine would send me into panic attacks and racing thoughts. Then, prior to the bipolar diagnosis I was on an SSRI with made things 1000 times worse, and if I added any caffeine I got so irritable I wanted to punch walls. Kind of the same thing with Lamictal for me, actually, in terms of irritability. After stopping meds, eating better, getting more sleep and lowering caffeine intake for awhile I can now handle it again. But, if I do too many days of caffeine in a row it kind of builds up and makes me feel irritable and perhaps hypomanic. I really cannot say what is hypomania, what is anxiety, and what is just caffeine sensitivity. I kind of blends together and I am just listening to my body and mind as best I can when it comes to caffeine.