Some authors think that REM sleep tones down emotions of memories, which makes it an attractive hypothesis for REM sleep to be the problem in patients with PTSD
Sleep disturbance (e.g., nightmares), as many know, is an intrusive symptom of PTSD. I, personally, do not know enough about the science of sleep--specifically, polysomnographic recordings--but I certainly believe it is possible that PTSD can impact REM sleep. After a quick review of recent literature there is some evidence for this claim.
Article Sleep and REM sleep disturbance in the pathophysiology of PT...