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Is your nervous system on high alert?

Updated: Mar 30, 2021

By Dr. Shawna Darou, ND

I want to start this article with the simple idea that the impact of stress on your body is not about how hard you work, but about how well you recover.

We’re living in a go-go-go culture, rushing from place to place, constant time deadlines, sensory stimulation around the clock, and work that doesn’t go away when you get home… Our bodies are designed to handle small, intermittent bouts of stress, but when stress becomes chronic it can lead to all sorts of issues – cognitive, emotional, physical and behavioural.

Your nervous system at work

In this article we’re talking about the autonomic nervous system, part of your peripheral nervous system which regulates various body processes without conscious effort. It is responsible for functions such as your heart-rate, respiratory rate, pupil response, and body temperature to name a few.

The autonomic nervous system has two branches: the sympathetic nervous system (“fight or flight”) and the parasympathetic nervous system (“rest and digest”). The sympathetic nervous system is activated with stress, especially stress that is perceived as danger. In this case, digestion slows down, blood flow is diverted towards skeletal muscle, and most non-essential functions of the body are shut down. On the other hand, when the parasympathetic nervous system is engaged, digestion is enhanced, you sleep deeply, and repair mechanisms in the body are activated.

Outside of real danger, we actually fluctuate between these two states regularly through the day because the sympathetic nervous system is part of how we mobilize the energy to get things done, focus on a task, and get through a hard workout. An ideal balance between these two branches is 2-3 hours of sympathetic nervous system response – going, doing, activity, focusing; followed by 20-30 minutes of parasympathetic nervous system response – relaxing and digesting. Unfortunately, most of us don’t live within this type of balance, because we are constantly triggered by stressors: our busy lifestyles, deadlines, time constraints, phones ringing, loud noises, emails coming in, etc.

Fluctuations in your menstrual cycle

You may also find it interesting that the autonomic nervous system and hormonal systems are connected. Estrogen increases activity of the parasympathetic nervous system via the vagus nerve, while progesterone has an opposite affect. This is seen through studies looking at heart rate variability, which is a simple measurement of vagal activity.

In other words, in the follicular phase of your menstrual cycle (day 1 to 14), there is an increased parasympathetic nervous system response, higher vagal tone and increased heart-rate variability – more calm and relaxed, better digestion.

And conversely, in the luteal phase of your menstural cycle (day 15-28), there is reduced parasympathetic activity, reduced vagal tone and lower heart-rate variability – more easily stressed, more anxiety, but also better mental focus.

Polyvagal theory – the third part of nervous system regulation

I’m going to briefly introduce another aspect of nervous system balance, because it is extremely important when we’re talking about tools for nervous system regulation. “Polyvagal Theory” was introduced by Dr. Stephen Porges as a third type of nervous system response acting through the vagus nerve. The vagus nerve, or more precisely the ventral branch of the vagus nerve controls the muscles of the face, heart and lungs – the parts of the body we used to interact with others in social engagement. According to Dr. Porges, social engagement calms or down-regulates the sympathetic nervous system and the fight or flight response.

In other words, when we are under stress – physical or psychological, the vagus nerve plays a big role in our physiological response and perception of stress, and this is very much influenced by our connection with others, our face-to-face social interaction and feelings of safety.

[This is an extremely brief and simplified introduction to Polyvagal Theory, and if you’re interested to learn more please see the references below.]

Signs that your sympathetic nervous system is dominant and out of balance:

When we get out of balance with chronic stress or simply a non-stop lifestyle, the sympathetic nervous system dominates and you start to face the world on hyper-alert. If you experience the following on a regular basis, you may be living in a state of sympathetic dominance:

  1. Unable to relax

  2. Startle easily

  3. Cold, clammy hands and feet

  4. Anxiety

  5. Insomnia

  6. Acid reflux

  7. Heart palpitations

  8. Headaches / migraines

  9. Poor digestion (often constipation)

  10. Hypoglycemia

  11. Frequent urination

  12. Sensitive to bright light

  13. Lump in the throat sensation

  14. Pounding heart when you lie down in bed

Simple Strategies for Nervous System Balance

If you have identified with a strong sympathetic dominant response, you’re certainly not alone. I believe that with current society expectations this has become the norm. The good news is that there are some very simple practices that can help to rebalance your nervous system, and these can make a profound impact on your stress levels, anxiety, sleep, digestion, and more.

(1) Taking breaks regularly through the day

Remember that your nervous system has a rhythm, and if you can build in regular breaks to reset you are essentially creating balance in your nervous system. Set a timer every 3 hours, and take a break: breathe fully, relax your shoulders, get a breath of fresh air, stretch, socialize, make a cup of tea,… These simple resets will improve your productivity and have a great impact on your overall stress level by the end of the day.

(2) Practice breathing with a slow exhale

We can influence the activity of the vagus nerve, which down-regulates the sympathetic nervous system with our breath. With deep, intentional breathing and a longer exhalation, you are eliciting a relaxation response almost immediately. When you’re taking conscious breaks through the day, practicing a few minutes of 2:1 breathing: breathing out twice as slowly as breathing in, you can improve the relaxation response.

(3) Learn about heart rate variability (HRV)

Heart rate variability is a measurement that is available through many devices and applications. It is a powerful way of measuring overactivity of the sympathetic nervous system, and more importantly learning techniques to regulate it. A healthy, relaxed person has high heart rate variability, which means that amount of time between each heart beat is different with each beat. Low heart rate variability is a sign of intense stress. When your sympathetic nervous system is under stress, your body will release stress hormones, and your heart develops an inflexible unchanging beat. You can learn more about tools and practices for heart rate variability here:

(4) Maintain social interactions

Remember the “polyvagal theory” mentioned above, and the role of social interaction in vagus nerve activity. As mammals, we require the presence of others: eye-contact, physical contact, in-person conversation to down-regulate the sympathetic nervous system. Texting and social media connection do not provide the same nervous system response. It’s important not to underestimate the importance of friendships, community and connection.

In conclusion

As we finish this brief article, remember that what we are seeking is balance. Your sympathetic nervous system at its best is energetic, gets things done and feels good, especially when the vagal tone is strong to dampen the response. When the sympathetic nervous system is in overdrive, we are constantly stressed, and not taking the time to relax, it begins to impact our health and well-being.

From all of the recommendations above, the simplest way to start is to remember to build in conscious breaks. Time to decompress, breathe fully and deeply (with a slow exhale), be with people who make you feel safe, and schedule these breaks at regular intervals. Remember that it’s not how hard you work that influences your body’s response, it’s how well you come down from stress that counts.

What’s Next?

Book an appointment with Dr. Darou online. Contact us: 416.214.9251, Resources – Polyvagal Theory:

This article glanced over the very important and innovative work of Dr. Stephen Porges. If you would like to learn more about polyvagal theory, here are some references:


  2. The Polyvagal theory: new insights into the adaptation of the autonomic nervous system:

  3. The Polyvagal Theory: Neurophysiological Foundations of Emotions Attachement Communication Self-Regulation – book by Dr. Stephen Porges

Disclaimer Please note that content on this website is indented for informational purposes only, and is not intended as a substitute for the advice provided by your physician or other healthcare professional. Do not use the information on this web site for diagnosing or treating a health problem or disease. Always speak with your physician or other healthcare professional before taking any medication or nutritional supplement, or using any treatment for a health problem. If you have or suspect that you have a medical problem, contact your health care provider promptly. Do not disregard professional medical advice or delay in seeking professional advice because of something you have read on this website. Information provided on this website DOES NOT create a doctor-patient relationship between you and any healthcare practitioner affiliated with our website.

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