narcolepsy
"Compared to ritalin, which I was taking before this drug, this produced a much more alert and natural awake feeling. Unfortunately for me it also made me practically psychotic and in a moment of thoughtfulness I thought this must be how people feel when they talk about "snapping". I could not control my emotions. I went back to my doctor and promptly switched off the medication. Too bad the side effects were over the top as the alertness was amazing. I took the drug for less than two weeks."