narcolepsy
"I was diagnosed a Narcoleptic at 11 and have, in the past 54 years, eaten amphetamines...Ritalin, Provigil, Nuvigil, tried GHB therapy...any number of variations of stimulating drugs...ALL with the same result: they all work to a degree...then fail as my body adapts to them; and none, working at its best, would be considered to promote a "normal" pattern of sleep and wakefulness. I'm using Nuvigil at the moment; and, while I know it will ultimately fail, the effect is of relatively transparent action - wakefulness, with occasional moments of connectedness, awareness of an extraordinary degree. I can see why it would be easily abused, or combined with other substances for abuse. Space limitations at this site: I will make another post soon."