How hard is it to get a special issuance from the FAA for Sleep Apnea? 

Depends. Will require a sleep study and paperwork. One of our pilots has been waiting since December. We had another a couple years ago that took about 90 days to clear. Then annual data download from CPAP to verify compliance. 

https://www.faa.gov/ame_guide/dec_cons/disease_prot/osa

Keep your mouth shut during your physical.

Plan on a type 1 or 2 in-lab sleep study at which you’ll be in a hotel room type study room with about 25 leads connected all over your body. Head, neck, chest, legs, and two nostril canules, and be expected to sleep. A tech watches you all night with cameras recording all of your movements.  It will cost you about $1,000 and take several  weeks to schedule and even more weeks to receive the results. They will ALWAYS say you have sever apnea.

Once you get an SI answer from the FAA in about 90 days you will have to show you wear your CPAP at least 6 hours per night. If you thought you were daytime tired before, well son, you’ll barely sleep at all with that uncomfortable contraption hissing all night.

At least annually and in some cases monthly you’ll need to provide your AME with data from your CPAP.

Otherwise it’s pretty easy.

The hasn't come up to me and forced me to do a sleep study yet. What did you do to need one?

A word of caution to all, dont ignore sleep apnea like I did. I now suffer from thick heart disease and enlarged veins that causes angina. My pilot license is now just another piece of paper in my wallet for I can never get a medical again. I hated the $800 out of pocket the insurance didnt cover for my sleep machine and hated wearing it so much I refused and now I am paying the price. Just something for yall to chew on. 

Was already on a special for a chronic lung issue, under control.  My Pulmonologist thinks I have the sleep apnea (6 months into my medical). I do the study, covered by insurance mostly.  Get a CPAP.  Call my AME, he says report it on next exam, which I do, with study results and usage reports etc.  At exam he issues medical, sends in Special paperwork, with all the required information, get the special in a few months.  Didn't miss a day of work.  That was 7 years ago, the FAA knew what I did and when I did it and still had a medical so it seems ok to me.  I found the full face mask was easier than the nose pillows, it stopped my snoring.  I was lucky it wasn't that hard for me.

How does one get diagnosed with sleep apnea?

Usually it starts with severe snoring.  When is it severe?  Ask your wife.  Also, with that is significant somnolence.  Somnolence = sleepiness, but is often confused with fatigue.

Another way is by simply measuring your neck.  A neck circumference of over 18 (or maybe 18.5) is an indicator it's likely.  There was a proposal to have all truck drivers have their necks measured at their DOT physical and referred for sleep studies if it was too big.  Don't know what happened to that.

Often a spouse complains about snoring and breathing then reads a bunch of nonsense about how every ailment deadly or not is directly linked to sleep apnea. After which the easy type 3 test that can literally be administered by a dentist will always reveal some apnea that can be cured with a dental mouthpiece that won’t really work that eventually leads to another test and BAM!! you’ve got a CPAP and an invitation for a special issuance second class.

Wanna know just how lucrative the apnea market is? Dana White and Joe Rogan are pitching a device daily.

I'm over 60 and in perfect shape. Fly at a great job. I recall my AME asking me if I had sleep apnea? I said what the hell is that. He said "that's a no". I asked him to explain. He said some people stop breathing while sleeping. I said WHAT!!!!!???. He said he was required to ask. We laughed and I left.

We must have had the same AME

... will cure Sleep Apnea