What Is Trauma?

Whenever a person feels overwhelmed and helpless in the face of a situation that is perceived as (life)threatening and is unable to respond to it, there is a chance that a trauma will develop.
But not only war, natural disasters, violence or abuse can activate traumas. Even everyday situations can be traumatic triggers. These include loss of a close person, (traffic) accidents, falls, injuries, serious illnesses, medical examinations, surgery and dental treatments, especially if the procedure is invasive and/or requires anesthesia.

In the face of a (life)threatening situation, the organism mobilizes a tremendous amount of energy to extricate itself from the situation by fight or flight (two of our instinctive innate survival strategies). If this succeeds, the mobilized energies are discharged by the action, and the body returns to its natural equilibrium.
If fight or flight is not possible, the body goes into the freeze response (our third instinctive strategy). The entire energy mobilized for fight or flight response is hidden under the torpor. If the organism can discharge this energy after the end of the threatening situation (e.g. by shaking or trembling), the body returns to its free, natural equilibrium.
In humans, however, this "post-processing" often fails when the mind inhibits instinctive behaviors. Thus, the energy remains trapped in the nervous system and can cause traumatic symptoms.

Therefore, trauma means "a biologically incomplete response of the body to a situation perceived as life threatening"  (P. Levine), an interrupted instinctive act.
This means that the results of trauma can heal if the bodily response is completed.