The Effect of Chronic Stress on your System Functionality
The neuroscience behind how holistic modalities such as breathwork, meditation and yoga manage chronic stress and anxiety.
12/17/20235 min read
The Fight/Flight/Freeze Response
A fight, flight or freeze response activates when the body perceives danger. This response essentially signifies ringing alarm bells to spring us into defensive action. This danger could be very real (like encountering an aggressive wild animal) or the stimulus just has to be perceived as threatening. In modern day life, we encounter very different and more complex stressors than our ancestors did and our alarm bells can become triggered more often throughout the day due to our systems “overreacting” to perceived dangers. For example, sudden noises for our ancestors signified real immediate dangers but nowadays, constant phone and email pings demanding our attention can subtly trigger a stress response.
An acute stress response would traditionally appear as one of these options: fight, flight, or freeze. Fight indicates combatting the perceived threat. Flight indicates creating distance between yourself and the threat. And freeze indicates an inability to act against said threat by going tense, still, and silent.
However, in the absence of a real threat, someone exhibiting the fight response can exhibit irritable or argumentative behavior.
The flight response can look like escape behavior and/or a reluctance to engage in activities even when safe.
And the freeze response can manifest as a feeling of numbness or immobility.
The Brain Stress Response System
The areas of the brain associated with the stress response include the following:
prefrontal cortex: higher order executive functioning
amygdala: emotional processing
hippocampus: learning and memory
hypothalamus: hormone production that controls body temp, heart rate, hunger, and mood
pituitary: growth and metabolism
brainstem: direct projections into lungs, heart, gut, etc. that allow physiological reactions
The autonomic nervous system is made up of the sympathetic nervous system and parasympathetic nervous system (as well as the enteric system but we'll discuss that another time). When the sympathetic NS is activated, our fight, flight or freeze response is triggered. This response speeds up our heart rate, increases blood flow to areas of our body that need more oxygen and overall ramps up the body into a state that can help us better deal with immediate danger.
The parasympathetic NS acts as break to the sympathetic response and is involved with rest and recovery. It regulates digestion, heart rate, and breathing.
Hypothalamus Pituitary Adrenal Axis
In addition to PNS and SNS involvement, the acute stress response involves the hypothalamus and the pituitary gland where hormones are released, activating ACTH by acting on the adrenal cortex to release cortisol (the stress hormone).
The hypothalamus pituitary adrenal axis is coordinated with the prefrontal cortex and amygdala. First, the amygdala detects a scary stimulus, then the prefrontal cortex regulates and dampens the stress response by making things seem less scary. The hypothalamus then "wakes up" the pituitary to release the hormones.
These systems are complex and designed for acute stress responses (immediate dangers/exercise), and chronic stress can produce alterations in homeostasis and system functionality.
Stress systems activate SNS, PNS, and HPA axis and put the brake on the inflammatory dampener to elevate levels of inflammation in the body. Chronic stress will continue to increase levels of inflammation in the body over an extended period of time.
Effects of Chronic Stress
Chronic stressors such as inadequate sleep, poor nutrition, and emotional distress impact our brain systems and can cause:
Decreased attention
Decreased perception
Decreased short term memory
Decreased learning
Decreased word finding
When our sympathetic system becomes activated, the parts of the brain responsible for intelligent thought go offline and we react out of the more primitive and instinctual parts of the brain. Instead of responding to life as it presents, we respond based on past experiences.
The Brain-Stress Loop
Our brainstem is like a bridge that connects our brain with the spinal cord, telling the heart to pump, lungs to breath, and gut to digest. The brainstem and bodily organs are connected by the vagus nerve, a bundle of nerves that tells most of the muscles in your body when to constrict, release, move, and relax and settle. This is how the body and brain communicate sensory information.
The vagus nerve carries 80-85% of information from the body to the brain and when stimulated, activates PNS through heartbeat, breathing, etc. This means that most of our sensory information travels upstream rather than the opposite. When the body is in a chronically stressed state, the brain is constantly being sent information that indicates danger. This alters the brain chemicals modulating cognition and mood, impairing judgement, depression, negativity, and dysfunction of our neural circuits.
The brain will then continue to activate stress response systems in the body, creating a loop.
Neuroplasticity
Brain cells communicate through neurons. Neurons communicate with each other through synapses where neurotransmitters are released to activate another neuron in that synapse & send information. Neurotransmitters are chemicals that carry messages from one neuron to another across the synapse. Receptors are protein molecules that receive and translate the chemical message.
The synapse is where neurons talk to each other constantly but never touch. Two neurons meet at synapse and special chemicals called neurotransmitters carry the message across the synapse.
Neuroplasticity is the feature of the brain that strengthens the connections between two neurons or generates new pathways that become useful or needed. This can be both structural as well as functional. Neuroplasticity also tends to prune off or alter neural pathways that we no longer use. Modalities that focus on the breath such yoga and meditation allow changes in the mind body by positively influencing how neuroplasticity occurs.
Yoga and the Breath
A yoga practice enables the practitioner to move in a controlled manner into modifiable physical postures concentrating initially on relaxing their body, breathing rhythmically, and developing awareness of the sensations in their body and thoughts in their mind. In addition to the physical benefits from sequentially completing the postures, the breathing and meditation exercises included in yoga are practiced to calm and focus the mind and develop greater self-awareness are tied with cognitive processes, emotional functions, neuron functions and communication
Yoga combats the stress loop by:
routinely calming the PNS
improving structure and function of brains areas such as:
the prefrontal cortex
hippocampus
amygdala
brain networks like the default mode network
creating sympathetic and parasympathetic balance
increasing neuroplasticity and strengthening neural circuits
Increasing homeostasis and balance
enhancing attention, emotional regulation, and memory
The breathing center is in the brainstem (pre-botzinger complex) and works with the amygdala and hypothalamus. The breath is controlled by the autonomic NS, so it happens naturally without having to control it. When the sympathetic NS is activated, the breath becomes rapid. When the parasympathetic NS is activated, the breath becomes slower and longer.
However, since we can also consciously control the breath, we have the powerful ability to directly influence the autonomic NS through manipulation of the breath, like a remote control. Rapid breathing will increase sympathetic activity while slower, mindful breathing reduces blood pressure and alters the information being sent to the brainstem. Inhalation increases heart rate and exhalation decreases heart rate. So, if we consciously lengthen our exhalation compared to our inhalation (twice as long is recommended), we can effectively stimulate the parasympathetic NS response to relax our mind and body. By cultivating the skill of breath control, we gain immense control over our mental and physical faculties. Control of the breath is the key to bringing the higher brain functions online when we have fallen into our patterns of activation and reactivity. It is imperative that we can learn to use our breath to help regulate our mind body systems living in fast-paced modern society where we constantly bombarded with stressors.
Stress is a reaction to demands or any real or perceived danger
There are three important things to note:
Stressors affect everyone
Not all stressors are bad
There are ways to manage stress
References
Conference for Research by Dr. Abha Rajbhandari. Brain and Body Functions in Anxiety.
Gothe NP, Khan I, Hayes J, Erlenbach E, Damoiseaux JS. Yoga Effects on Brain Health: A Systematic Review of the Current Literature. Brain Plast. 2019 Dec 26;5(1):105-122. doi: 10.3233/BPL-190084. PMID: 31970064; PMCID: PMC6971819.