I have been on adderall 30mg for 18months. Last month I noticed a signifigant difference in my ability to concentrate. I was wanting to go to sleep by noon and by 5:00 I felt horrible. This month I did not take the medication for a few days and can say I did not notice any difference from when I do take it. People I work with have asked what is wrong with me. I am disorganized, not focused and tired. Has something changed with the generic adderall tablets?