PTSD and sleep apnea - any correlation between the two?

I have a great deal of trouble sleeping. Anxiety makes my sleep restless and difficult. But now I have been told it may be sleep apnea and am presently awaiting results of a sleep study I just took.

I remain convinced however that it is my panic and anxiety that has the greater impact.

I am just wondering how common sleep apnea is amongst those with PTSD.