People who attend other people's worst days accumulate the effects of it, and the professions that do it most are the professions least willing to say so.
What is normal in the days after. Broken sleep, replaying it, irritation out of proportion, avoiding a road or a smell, feeling numb, or feeling nothing and being troubled by that. Most of it settles.
What is not, and needs help. It getting worse rather than better after several weeks; nightmares and intrusive images that do not fade; drinking more; avoiding work or people; anger that frightens the people around you; thoughts of harming yourself.
A single mandatory debriefing session is not the answer. Requiring everyone involved to sit down and recount the event in detail once, shortly afterwards, has not been shown to prevent later problems and may make some people worse. What helps is practical support, rest, being able to talk to people who understand the work when and if you want to, and access to proper care for the minority who need it.
What actually helps.
- Sleep, food, and being taken off the rota rather than being told to be fine.
- Talking on your own terms, to peers or to somebody outside the work.
- Knowing what happened afterwards — the outcome — where that can be shared.
- Limits: on shifts, on exposure to graphic material, on how many of these in a row.
- Asking somebody directly if you are worried about them, in the words of the previous lesson.
For anybody reviewing graphic material as part of an investigation: work in short sessions, turn off autoplay, mute by default, view stills rather than video where it is enough, and stop when you notice you have stopped reacting.
Source. World Health Organization, War Trauma Foundation and World Vision International, Psychological first aid: Guide for field workers, https://www.who.int/publications/i/item/9789241548205 ; WHO mhGAP, https://www.who.int/teams/mental-health-and-substance-use/treatment-care/mental-health-gap-action-programme
What this is not. Reading, not training, and not mental health care. If any of the second list applies to you, the useful action is to see somebody qualified.