Well, it makes sense to me. Honestly, having suffered several tragedies in my life(havin mild PTSD), not to be disrespectful to the people doing these studies and spending tons of money on 'em but the answers free and just under our nose...... YES!!!! My dad is a Vietnam Vet and has major PTSD, sleep especially deep REM sleep, hits the dream stage and wham there you go. Sometime during that cycle it will surface. He sleeps in  2 to 4 hour increments, he has an automatic alarm he has created over the years.He wont take heavy meds to sleep because he is afraid of what might happen. Me and my sister have managed to get him to when he hasn't slept good for a few days and we stay with him at his house with him, I think this too subconciously helps him feel protected and safe.Sorta like when in Vietnam when you slept someone else was on guard duty.... And this is just a "laymans" observation and experience. I agree totally there needs to be better meds for treatment but a solution would be best.... PTSD is NOT a joke or to be taken lightly, even though I showed humor in my comment. It is a coping skill I have created for me and my life.Thank you for sharing this info. Please excuse my soapbox mentality, as you can see stuff I'm passionate about really makes me yap!!!