Stress and trauma are gradually being recognised as the underlying causes of much physical disease and mental health issues. Bessel van der Kolk has been a huge contributor to this movement with his book The Body Keeps the Score, building on the work of Peter Levine and then followed by Stephen Porges and Stanley Rosenberg.

From the brain the central nervous system communicates with the major organs of the body in a number of ways, in particular through its close interaction with the endocrine system and the hypothalamic-pituitary-adrenal axis. This HPA axis links the electrical impulses of the brain and our nervous system with the chemical reactions of the body, via the hormones produced in the endocrine system.

One distinction which is of great relevance to our health or disease, is the sympathetic versus the parasympathetic nervous system within the autonomic nervous system.

When the body is under stress and agitated the hypothalamus (about the size of an almond) in the limbic brain activates two systems in combination: the sympathetic nervous system and the adrenal-cortical endocrine system. Initially the hypothalamus releases the main stress hormone, corticotrophin-releasing factor (CRF) into the sympathetic nervous system, leading to what is known as the fight or flight response. The stress chemicals released have the following impact:

1. The blood vessels travelling to the heart, large muscle groups, lungs and brain dilate.
2. Your heart and respiratory rates increase and your muscles tense.
3. Your pupils dilate so that more light can get in.
4. Glucose is released into the bloodstream giving you a boost of energy.
5. The blood flow to the gastrointestinal tract, hands and feet is constricted.
6. The level of acid in the stomach increases and digestive enzymes decrease.
7. Cortisol suppresses the proliferation of lymphocytes and reduces their function, thereby lowering the immune system in order to conserve energy reserves.
8. The reproduction system gets shut off.
9. Blood flow is redirected to the hindbrain enhancing the hindbrain's life-sustaining reflexes to ensure our short-term survival.
10. The adrenal stress hormones constrict the blood vessels in the forebrain reducing its ability to engage in conscious action, reasoning and logic. So there is a diminished ability to think clearly.

The result is that we are in the physical state of fight or flight, accompanied by brain fog.

Stanley Rosenberg notes that Flight is not only the act of running away – it includes actively avoiding people, situations, or places. It can be simply withdrawing from social situations by watching television or taking part in other solitary activities, possibly driven by anxiety or panic attacks.

If the danger then subsides or is resolved, the hypothalamus stops triggering the stress responses and the sympathetic nervous system shuts off again.  Our cortisol and adrenaline levels naturally drop. Our heart rate and breathing decrease, our blood pressure drops and the immune, digestive and reproductive systems switch back on. The ventral vagal branch of the parasympathetic system takes over.

However, if the fear-inducing situation is not resolved but indeed escalates, the next stage is defined as true trauma, activating the dorsal vagal branch of the parasympathetic nervous system, which I will discuss in the next blog.