I have a theory why profilers may not suffer as many nightmares as you might expect, given the nature of their work, as people in other professions who also deal with death and carnage all the time such as EMTs, police, combat soldiers, etc.
Freud was wrong about a lot of things, but he was right about some things as well. What he believed about dreams as related to the conscious and subconscious always made sense to me in one respect. One of his many original thoughts on dreams was that if a person had sufficiently processed a subject or experience during waking (conscious) hours, the subconscious would have no need to explore it in sleep.
As opposed to other professions that bring people into contact with an abnormal amount of death, carnage and criminality, profilers, by the very nature of their investigation and research, spend hours in their head processing every piece of the puzzle trying to understand the crime and criminal. Other professions often encounter all the same elements, but it’s not in their job description to reason why, and they may not have a natural proclivity to do so. I would think these people, because they may rarely completely process what they saw, or may never have the opportunity to know any more details, would be more apt to have nightmares, because they have been exposed to something traumatic, and their subconscious will deal with it if their conscious doesn’t.