These two go together - set and setting.

For lessening the effect of traumatizing experience, 40mg of propranolol an hour before remembering and visualizing the traumatic, under guidance of a therapist, should be the gold standard for treatment. There a lot's of researchs showing its effectiveness but for some reason it's use stays experimental. I suppose it's because there is no money to be made with an old drug cheaply available from many generic suppliers.