The causes of stress have changed and developed through evolution, yet the bodily response to external pressures and threats has not. When the mind perceives a threat whether it be physical such as thinking a snake is about to bite; hypothetical, thinking a boss is going to get angry at a missed deadline; or emotional, such as relationship problems, the body reacts in the same way.
The body’s fight or flight response is automatically activated by the brain without conscious awareness. The hypothalamus a small but critical part of the brain activates two systems, the sympathetic nervous system and the adrenal-cortical system.
These two systems instigate a number of potentially lifesaving changes in the body. Once the threat has been eliminated these systems also help to ‘turn off’ the stress response and aid the body return to its normal state of balance and metabolic equilibrium, a process known as homeostasis.
The hippocampus is another small but very powerful part of the brain that controls the parasympathetic nervous system (PNS) and aids memory and learning. The PNS promotes relaxation, calmness and a homeostatic state within the body, a condition in which processes such as digestion and rejuvenation can occur. After a stress response however the body remains on a higher state of alert and readiness for some time before it completely relaxes.
Mental and physical problems with stress occur when the body is constantly in a state of fight or flight and when it does not have enough time to relax, rejuvenate and return to a state of homeostasis after a stress response.
If the stress hormones involved in the fight or flight response are active in the brain and body for prolonged periods of time, they can cause neuronal cell death particularly in the hippocampus and can inhibit the regeneration of new cells thus having a direct influence on memory and learning.
The sympathetic nervous system has a hierarchical dominance over the parasympathetic nervous system, this means it often requires conscious intention to relax and reinstate a state of metabolic balance and harmony.
Mindfulness meditation has been shown to help calm the body. It teaches individuals how to live in the present moment and become aware of thoughts, feelings and bodily sensations in a non-judgemental way.