Don't know about obstructive sleep apnea, but sleep apnea & other sleep disorders are a very real problem. When you spend 20 years working the wrong side of the clock, living in field conditions, waking to gunfire, back and forth over multiple time zones, flipping sleep schedules daily and routinely (day flights, night flights, day flights) within the same few days, flying max duty days continuously (16-18+ hours), poor nutrition, living conditions that require continuous wearing of combat gear, sleeping in tents/aircraft/outdoors, communal living, routine minimum rest prior to flying, working to within minutes between duty days, etc.

I could literally keep typing and fill this page, but I hope you get the idea. Virtually every single person who does 20 years in the military and has had the deployment schedule we've all had over the past 15 years has some form of sleep disorder - whether it's true apnea (central or obstructive) or some other sleep disorder is for a sleep expert to determine. What cannot be disputed is that the overwhelming majority of military veterans have some sort of sleep issue or other.