The Nervous System & Stress

“Mental Health problems are Nervous System Dysregulation”
–Dr. Nicole Lepera

What is the Nervous System?

Central Nervous System

Peripheral Nervous System

The Autonomic Nervous System

The autonomic nervous system (ANS) is part of the peripheral nervous system, and is responsible for the control of vital functions such as heart beat, breathing and digestion. It is also involved in the acute stress response where it works with the endocrine system to prepare the body to fight or flight. It can be further subdivided into the sympathetic and parasympathetic divisions.
Guy-Evans, O. (2021, April 28). Autonomic nervous system: definition, division and function. Simply Psychology.


 A generic overview of the stress response system.

  • Fight: facing any perceived threat aggressively.
  • Flight: running away from the danger.
  • Freeze: unable to move or act against a threat.
  • Fawn: immediately acting to try to please to avoid any conflict.

When one feels threatened, the body rapidly responds to the imminent danger. The underlying goal of springing into fight, flight, freeze, or fawn, is to decrease, end, or evade the danger to return to a state of calm and control.

Acute stress response: When a stressor is perceived, the hypothalamus activates the sympathetic branch of the autonomic nervous system. This, in turn, causes the adrenal medulla to release adrenaline into the bloodstream. This prepares the body for “fight or flight”. The adrenaline and noradrenaline increase the heart rate and the breathing rate, the blood circulation is redirected to the skeletal muscles and the digestion stops.

When the stressor subsides the parasympathetic branch of the nervous system is activated and the heart and breathing rate decrease, the digestion restarts and all other functions go back to their normal level.

Parasympathetic branch of the
Autonomic Nervous System (ANS) 

The parasympathetic nervous system is a subdivision of the autonomic nervous system (ANS) which regulates bodily functions which are outside of voluntary control, therefore being automatic.

The parasympathetic nervous system is also referred to as the ‘rest and digest’ system as it functions to conserves the body’s natural activity, and relaxes the individual once an emergency has passed. The parasympathetic nervous system leads to decreased arousal.

The parasympathetic nervous system (PSNS) leads to decreased arousal on areas such as the eyes, glands that produce saliva, nerves in the stomach, blood vessels, and nerves that go to the bladder.

The PSNS begins in the brain and branches out via long fibers, which lead to connecting neurons that are near the organs they intend to act upon, enabling quick responses.

Frothingham, M.B. (2021, Oct 06). Fight, Flight, Freeze, or Fawn: What This Response Means. Simply Psychology.

What is nervous system dysregulation?
How do we recognize and re-regulate ours?

What is trauma?

“We become traumatized when our ability to respond to a perceived threat is in some way overwhelmed.” (Page 9, Healing Trauma, Peter Levine, 2008)

“The debilitating symptoms that people suffer from in the aftermath of a perceived life-threatening or overwhelming experience.” (p.7) “This perception is based on a person’s age, life experience, and even constitutional temperament.

“All traumatic events are stressful. Not all stressful events are traumatic.”(p.7)

“Many factors are involved on the wide range of response to threat which depend on genetic makeup, an individuals history of trauma, family dynamics.” (p.8)

“trauma can impact us in ways that don’t show up for years.” (p.9)

“trauma is about a loss of connection– to ourselves, to our bodies, to our families, to others, and the world around us. This loss of connection is hard to recognize because it doesn’t happen all at once.”

Why try to understand if you have been traumatized and/ have symptoms of trauma?

According to Peter Levine, it is worth trying to understand the possible causes of trauma and identify various symptoms that may have arisen as a result. Symptoms of trauma– that loss of connection to ourselves and the world, “can happen slowly over time and we adapt to these subtle changes sometimes without noticing”– and “these are hidden effects of trauma that can gradually undermine our self-esteem, self-confidence, feelings of well-being and connection to life. Levine says “our choices become limited” as we may avoid certain people, certain feelings, places, and situations which is a “gradual constriction of freedom” and thus “a loss of vitality and potential for fulfilling our dreams” and creating the life we desire(Levine, p.9).

**Your “not feeling quite right” could be the result of trauma without you knowing it– which is why I am sharing this information with everyone, not just the clients I see who have asked for help with mental health issues. **

If you aren’t traumatized, why should you know what trauma is?

How to understand and be compassionate to people who suffer with PTSD and traumatic stress in their systems– what their paradoxical or incongruent/irrational and overly reactive or under-reactive behaviors might mean, and how you can tell and how you could help.

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