Matthew
Touchdown! Greaser!
What I really dread is a possible diagnosis of "mild" OSA. That's the worst of all. If your problem is more severe, you get a CPAP and you get your SI. If they don't decide it's bad enough for the machine, you get to do the maintenance of wakefulness test like one friend of mine. He described it to me, and it sounds like even someone with no OSA at all who got a great night's sleep would have trouble staying awake!
Not a doc - my understanding: a sleep study will count apneas (among other things). An apnea is a breathing episode that lasts > x seconds. For a diagnosis of OSA, you need > y apneas per hour. I don't remember what x and y are, but it should be easy enough to Google. Doc Chien can answer this - I think FAA sees any OSA diagnosis as something that must be treated and doesn't differentiate between mild or otherwise. The treatment also has to have some way to record compliance, so you need a recording CPAP. FAA doesn't like dental devices that hold your jaw just right or tennis balls sewn into the back of a t-shirt so you are forced to side-sleep because there is no way to record that you actually are using those methods.