What is trauma?
The American Psychological Association defines trauma as “an emotional response to a terrible event like an accident, rape, or natural disaster.” Life experiences like divorce, illness, and death can also be traumatic. You typically feel shock and denial following a trauma. In the long term, you may experience flashbacks, volatile emotions, and physical symptoms like headaches, nausea, and fatigue.
While these responses are normal, they can make it difficult to move on with your life.
What happens in your body when you’ve been traumatized
- Trauma triggers an overproduction of stress hormones — namely cortisol. If you are constantly reliving a traumatic experience, stress hormones remain activated, keeping you in a state of high alert.  You might experience trembling or an exaggerated startle response, especially to things that remind you of the traumatic event. These are called “triggers.”
You will enter the fight, flight, or freeze mode  whenever you feel triggered. What does this mean? You’ll feel compelled to either defend yourself against the trigger, run from it, or you could feel paralyzed. Sleep might be difficult and you may feel the need to avoid people or situations that you believe threaten your safety. 
Trauma affects three areas of the brain — the amygdala, the hippocampus, and the prefrontal cortex — and can create lasting changes in all three regions. Animal studies reveal that post-traumatic stress disorder (PTSD) can lead to significant changes in brain size and can impair brain functioning. Over time, the excess cortisol produced by the fight or flight response can actually rewire your brain’s circuitry, creating psychological and emotional distress. 
Trauma is linked to future health problems
Chronic stress following a traumatic event can have long-term health effects, including:
Heart and liver disease
Addictive behaviors like alcoholism and smoking
Chronic pain conditions
Anxiety and depression
Feelings of despair, guilt, and shame
Cognitive impairment such as memory lapses, difficulty making decisions, distractibility, withdrawal from your typical routine, and even a lost sense of time