Welcome to the PEB Forum!
Hmm, indeed, a very good question...
It seems many military veterans are unaware that if you are military service-connected for PTSD, you can
also file a DoVA claim for veterans disability compensation on
sleep apnea as secondary to PTSD. If you are claiming sleep apnea as secondary to PTSD, then you should already be rated as military service-connected for PTSD. If not, then you must organize and word your DoVA claim carefully, so it is
very clear to the VA rating officer that he/she must
first determine your claim for PTSD, and only
then consider your sleep apnea.
Once you are military service-connected for PTSD, you need to show that it is "as likely as not" that your sleep apnea is somehow related to your PTSD. There have been numerous journal studies performed which determined a strong correlation of comorbidity between PTSD (or any other anxiety/mood disorder) and sleep apnea.
To that extent, one piece of evidence that will help your DoVA claim is having your doctor write a letter saying exactly what the journal study states: based on the science, "it appears to be as likely as not that your sleep apnea and your PTSD are related conditions." Remember that since this is a VA claim for a secondary condition, you are trying to prove the connection between sleep apnea and your military service-connected PTSD,
not the direct link between sleep apnea and your military service.
As such, the doctor's examination is critical to your VA claim for a secondary condition. If the doctor who examines you believes it is at least "as likely as not" that your sleep apnea is related to your PTSD (and he/she will put that in writing), then you shall have a strong VA claim that is likely to be granted.
Bottom line is that if you have PTSD and Sleep Apnea, then you can now file a DoVA claim for the sleep apnea as a secondary to your PTSD if applicable.
In retrospect, I have been diagnosed with PTSD and Obstructive Sleep Apnea with CPAP while still on active duty in the U.S. Army with both medical impairments being designated as related conditions and military service-connected by the DoVA D-RAS. That said, I am currently generating a DoVA claim inclusive of
sleep apnea as secondary to PTSD in the forthcoming submission of a new VA disability compensation claim. More to follow upon receipt of updated VA claim information.
Thus, I quite often comment that "possessing well-informed knowledge is truly a powerful equalizer!"
Best Wishes!