I would say to do a little more research and find out exactly to whom you're marketing. The reason I say this is that in the US the descriptive word for the affliciton rather than the person (or thing?) is far more common. There may be other regions where "narcolept" is used as frequently as, or more than "narcolepcy" or "narcoleptic". I'm thinking England, or maybe India or South Africa, to name a few possibilities.
Good luck with it.