A trigger can be from anything that sparks a memory of a trauma or part of a trauma.
The memory can be conscious or unconscious.
It happens when the brain, or more specifically, the limbic system in the brain recognises a similarity to something that happened before that harmed you and jumps into high alert to protect you.
A trigger can feel like a sudden explosion of anxiety or frustration with no understanding of where it came from.
This can cause a sudden, apparently obscure, change in behaviour.
The stimulus can be a wide range of things, a certain smell, situation, anniversary, mannerisms in a person, just to name a few, all can be a trigger.
Due to the emotion attached to the event, once triggered, it may feel as though you are reliving the traumatic event again.
Triggers are unlikely to be fully erased, yet can be diluted and managed.