I havent had the increased heart-rate, though the jitters, nervousness, and being "on-edge" keep me from taking it except on really bad days. (actually, lately I've just been using provigil). I highly recommend the provigil in that other than yucky metallic taste, headache, and sore-throat, it actually puts me in a good mood and takes away the cotton-for-brains (as long as I dont take it too often)... Hope this helps. Peace, Dave