Yes they can work. Although they should have support and justification when in crisis. And employers should be benefitiated for giving work to narcoleptics. Because in some periods you have crisis.
Stress is my first cause of cataplexy atacks, and so work can be very difficult and can be a mean of gettibg sick. Professions that should not be chosen are: bus,taxi, any veicule driver, doctor because you'll have blackouts, nurse, a profession where you deal with much stress like being a director of an enterprise, etc.
You should have the right to retirement when you already have a career. But if have some kind of timetable that can ajust or do some mechanical work, or can miss for some days your work, perhaps you can deal well with disease and your profession.