Can anyone report experience with Nuvigil (armodafinil) or Provigil (modafinil) for narcolepsy ?

I need to take a sleep study (thousands of $$$) which is apparently about the same process for sleep apnea or narcolepsy. If I have apnea, CPAP machines are the usual treatment; for narcolepsy, its Nu/Provigil (almost identical drugs). I'm trying to anticipate my options for either outcome, because I really can't afford the test right now (too young for Medicare, no insurance), and I have plenty of time to learn all I can about the treatments. If nu/provigil is prone to side effects, that might help me decide later. Thanks for any advice.

(both are Rx-only)