I was on the drug for more than a year, and never once experience even a minor amount of psychosis. It was only once sleep deprivation set in from overuse of the medication that symptoms of Psychosis began to appear. At one point I went more than 48 hours without even a moments sleep, and when I was sleeping it was usually less than 2 hours a day. This went on for almost 2 weeks. It was only once I averaged less than 1-2 hours of sleep per night for almost 2 weeks that any signs of Psychosis appeared.