I happen to be a person who is diagnosed with ADD/ADHD and I experience psychosis while taking the medication, and my doctors assumed that it was the medication that caused the psychosis. I can tell you first hand, that I had not slept more than 30 minutes a day in more than 3 days, and that Sleep deprivation was the cause of the psychosis and not the medication. Stimulant drugs can cause sleep deprivation, and sleep deprivation causes psychosis. The drug itself never once caused Psychosis when sleep deprivation was not present.