Updated: Jun 25
Stress is a word we hear so much in today’s society. The pace of life is so fast, we struggle to stop. The autonomic nervous system (ANS) is in charge of all bodily functions that we don’t have to think about, such as heart rate and blood pressure regulation, digestion, bladder control, respiration, sweating and our stress response. There are two branches, with the sympathetic nervous system (SNS) being our fight flight response, and the parasympathetic nervous system (PNS) for rest, digest and restore.
When the nervous system is well regulated, these systems will fluctuate through the day to meet the demands of the moment within an optimal window of tolerance.
The fight flight response is meant to be short term, but when the perceived or real threat is constant, the SNS becomes overactive constantly releasing cortisol and adrenaline - our stress hormones - resulting in a state of hyper-arousal. This may cause an increase in heart or respiratory rate, inability to relax, sleep difficulties, with associated feelings of anxiety, panic, hyper-vigilance and agitation.
For some people, chronic stress results in hypo-arousal, where the body shuts down, disengages, and becomes immobilised, with feelings of depression, apathy, or sadness. Other people will fluctuate between hyper and hypo-arousal, with both states indicating a dysregulated nervous system affecting our physical and mental health.
Our threats today may be current life stressors such as work pressures, challenging relationship, loss….. to name a few. Our personality type such as perfectionism, driven, need to be in control, people pleasing, anxious and analytical may create self-induced stress. Then we have past/childhood stressors or trauma, which may be buried deep in the unconscious mind, but our body remembers, which will have a lasting effect on our nervous system and influence how we respond to current stressors.
The immune system is closely linked with the SNS, and activated when we face a threat, to prepare for a possible injury or infection. Cytokinin’s are released which are anti-inflammatory. When the threat /stress is constant , pro-inflammatory Cytokines become dominant resulting in micro inflammation, which may account for the increase in allergies people experience today.
The Vagus nerve is the 10th Cranial nerve, that wanders around the body, driving the PNS. Vagal tone is the health of the autonomic nervous system, which can be measured by Heart Rate Variability (HRV). As we breathe in, our heart-rate speeds up, as we breathe out, it slows down. The higher our vagal tone, the greater the difference between our inhalation heart-rate and our exhalation heart-rate, therefore greater PNS activation. With a higher HRV we are likely to have better general health with increased emotional stability and resilience. A lower HRV is associated with poor physical and mental health.
So, what can we do in improve the health of our nervous system?
Spending time outside and being active is an excellent way to activate the PNS. I recently spent a week in Scotland for some Munro bagging. Prior to going, I was busy, running from one thing to the next, my mind cluttered with all I needed to do.
Walking in the mountains is a form of active mindfulness. There is nothing else to do in the mountains, other than put one foot in front of the other, looking at the beautiful landscape, hearing the Ptarmigan and the Deer, feeling the wind and rain in your face, hour after hour. It did not take long for me to feel calmer. Next time you are outside, take time to notice of your environment it has a powerful effect on your nervous system.
Breathing in and out through the nose along with belly/abdominal breathing will help slow down the respiratory rate and lower Cortisol levels. Spending time each day breathing at a rate of 4.5 – 6.5 breaths per minute has been found to optimise PNS/SNS balance and improve vagal tone.
I spend 10 minutes each day with a respiratory rate of 5 breaths per minute, using HeartMath breathing app, which also measures heart rate variability.
Here is the data I collected following my trip to Scotland. You will see that I am mainly green, which indicates a higher HRV, therefore I am in a more coherent state where the heart, mind and emotions are in sync. As a result, the immune, hormonal and nervous systems function work in harmony.
This is before I went away, spending less time in a coherent state.
Cold water exposure
Wild or open water swimming has become increasingly popular over the last few years with increased evidence for its health benefits. There are reports of symptom relief in those who have depression, anxiety, chronic pain, to name a few.
On initial cold water exposure, the stress response is activated releasing adrenaline and cortisol, but with regular exposure you become less reactive to the cold stress. This transfers to daily life making you more able to adapt to daily stressors.
Cold water exposure results in the release of endorphins, dopamine and serotonin which may help reduce pain and depression. The endorphins released also create a sense of euphoria also known as swimmers high. Inflammatory Cytokines decrease, therefore micro-inflammation is reduced, with regular wild swimmers reporting fewer and milder infections.
If the thought of wild swimming does not appeal, a 30 second daily cold shower, or even immersing your face in cold water may be enough to stimulate the vagal nerve, and therefore parasympathetic activation.
Wild swimming comes with risks and will not be for everyone. See here to learn more
I have only touched on a few ways the PNS can be activated focusing on being in nature, movement, active mindfulness, breathing and cold water exposure. There are many more:
Compassion for others
Music, singing, humming
Connection with others
About the author
Lorna Nicholson is a registered nurse (previously working as an advanced nurse practitioner in primary care), a body control Pilates Teacher, Buteyko Clinic Certified instructor, BASI level 2 ski instructor and Stress Induces Recovery Practitioner.
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