Hello. I've been taking Concerta for about 6 months. In the beginning I suspected my response to it was only psychosomatic but I stopped taking it a couple of weeks ago for three days just to see. I was extremely irritable and grouchy which is not like me at all. When I'm taking it I often feel hypersensative to everything that is going on around me especially when I drive. My appetite is nonexistant during the day which is not a healthy thing for me to begin with but it does reduce the compulsion to do other things like purge. I take 36mg (time released form) which is a fairly low dosage so I don't think the side effects are from taking too much. The Concerta makes me focus better and I'm able to organize my thoughts better than I ever have in my entire life. Lately my heart rate has been irratic almost resembling the symptoms of atrial fibrilation. I'm only 24 and am in the miltary so I'm very active. I'm afraid that my heart will explode one day while running. The benefits far outweigh the negatives so I guess what I'm getting at here is...Does anyone have similar experiences/fears with Concerta? Is there ever going to be a time where I will be able to function as well without the Concerta as I do with it? I really don't care for the whole drug dependence theory.