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How to lower your fear response

Amygdala highlighted in brain

The inspiration for this piece came from a section in the incredible book, Breathe by James Nestor. In it he shared a story of a lady with Urbach-Wiethe disease, a rare genetic condition that caused parts of her brain to harden, which completely destroyed her amygdala (our fear processing centre). As a result she has problems detecting danger and has absolutely zero fear. However, a simple experiment managed to trigger her fear response… a single inhalation of carbon dioxide.

Sounds bizarre, but it has profound implications for helping people learn how to lower their fear response and decrease panic and anxiety in their life. Find out why...

Sound the alarm

Back in the day (how far back depends on your view on evolution), the world was a dangerous place. Everything could kill you. Being able to identify things in our environment that could potentially harm us helped us survive by keeping us safe, allowing us to reproduce. This ancient threat detection and protection mechanism is the foundation of fear (which itself is the core of all anxieties). It’s rooted in one of the deepest, most ancient parts of our brain, the area that deals with memories and emotions, the limbic system.

Part of our limbic system is an almond-shaped cluster of nuclei known as the amygdala, which plays important roles in behaviour and emotion processing; two of which are the reflexive processing of fear and the forming of memories associated with fear-inducing events.

For a long time science has known that the amygdala is part of the fear circuit (once our sensory cortex has detected a threat, the amygdala can drive a response), but only more recently has it been discovered that the amygdala is also a threat sensor itself.

Our body contains special cells, known as chemoreceptors, that sense changes in oxygen, carbon dioxide and pH in our body. There are two types; arterial (found in our aortic and carotid arteries) and central (located at the base of the brain stem). The amygdala is packed with the latter, which detect changes in the pH of the cerebrospinal fluid.

Why would the amygdala need to sense these pH changes? Turns out they’re greatly influenced by changes in CO2 levels in our blood. Consider it our body’s ‘suffocation alarm’. If we don’t have enough oxygen (if our CO2 levels are too high), the amygdala triggers this primordial fear of suffocation as a warning to breathe more! It’s a survival mechanism.

Side note:

  • Carbon dioxide is an acid (low pH), so when CO2 levels increase, pH decreases and when CO2 levels decrease, pH increases.

  • Depending on the levels of CO2, our brain, via the central chemoreceptors, will either send a signal to our lungs to breathe more (to lower CO2) or to breathe less (to increase CO2).

  • This reaction plays a significant role in how we breathe, with central chemoreceptors controlling 50% - 90% of our breathing response to elevated CO2.

Constant state of fear

No doubt you’ve heard the expression ‘we’re living in a constant state of fear’? Unfortunately, that’s probably true for a lot of us, but not because of the news or social media (although they’re contributors), it’s because our bodies have become too sensitive to carbon dioxide.

While our lives may have less immediate, harmful threats (imminent death), this has been replaced with an increase in the number of imagined threats (uncertainty, insecurity, worry), and the body responds accordingly, triggering a fear response (a form of stress) to protect us from harm. A byproduct of this chronic stress is a vicious cycle of increased respiration (breathing too much). By breathing more than we need to, our bodies become less tolerant to CO2 and our chemoreceptors start sounding the fear response alarm bells at lower and lower levels of CO2.

There’s a term in neuroscience associated with learning and memory called long-term potentiation, or ‘a persistent strengthening of synapses based on recent patterns of activity’. Essentially meaning that the more you do something, the stronger the response to that thing will be. In the context of our fear response: the more scared you feel, the scarier things will feel. So because we’re continually primed for fear through poor breathing, previous harmless or insignificant threats may start to feel overwhelming. Our fear sensor becomes broken.

Fix the sensor

Have you ever experienced a sensor light going on and off all night due to the tiniest movement? If so, how did you fix it? Aside from smashing the globes, you most likely adjusted the sensitivity! The same applies in your body.

If your body is continually detecting elevated levels of CO2, triggering the panic alarm and causing you to breathe more, the solution isn’t to rip out the sensor, it’s to decrease the sensitivity.

How do you do that?

By teaching the body (the brain) to become more tolerant to carbon dioxide. You do this by practicing holding your breath, which creates a buildup of CO2.

3 Breath holding exercises

The following exercises are taken from the Oxygen Advantage.

*Denotes a variation

Small breath holds (warm up)

  • Suitable for all persons.

  • You can alter the intensity of this exercise by increasing the length of the breath hold slightly (no more than 10-15 seconds).

  • Duration: 2.5 minutes


  1. Take a normal breath in and out through the nose.

  2. Pinch your nose with your fingers and hold the breath for five seconds.

  3. Let go of your nose and breathe normally in and out through your nose for ten seconds.

  4. Repeat for five rounds.

  5. You should not feel stressed while doing this exercise. If the need to breathe is too strong, hold the breath for three seconds only.

Breathe Light

  • Suitable for all except those with serious health conditions and those in the first trimester of pregnancy.

  • Duration: 5 minutes


  1. Sit upright or lie on your back in a semi-supine position.

  2. With your mouth closed and jaws relaxed, breathe normally in and out through your nose, widening the space between your ribs on every inhale.

  3. Start by observing your breath as it enters and leaves your nose (use this as an anchor point if your mind starts to wander during this exercise).

  4. When you can comfortably follow your breath, start slowing it down, making your breathing light, quiet and still.

  5. The aim is to feel hardly any air entering/exiting your nostrils.

  6. It is very important not to consciously interfere with your breathing muscles or restrict your breathing during this exercise.

  7. Your breathing volume should now be less than what it was before you started the exercise (~80% of what it was).

  8. The goal is to feel a want or “hunger” for air. To have a feeling that you would like to take in a bigger breath. It should be tolerable.

  9. Maintain this feeling for the remaining time.

  10. If you notice that your breathing rhythm is getting fast or chaotic, then the need for air is too much. Stop the exercise and breathe normally for half a minute, then resume.

Breath holds while walking*

  • This is one I like to incorporate while on a walk as it ticks both the exercise and breath training boxes!

  • Not suitable for people with serious health conditions or who are pregnant or looking to conceive.

  • This exercise is only suitable for those with strong breath hold experience as there is a risk of passing out. Practice at your own risk.


  1. While walking, take a normal breath in and out through your nose.

  2. Pinch your nose with your fingers to hold your breath.

  3. Count your steps (I just count the steps on the same leg).

  4. Relax into the muscle contractions and bring a feeling of relaxation to your body.

  5. Continue to push the hold.

  6. When it becomes difficult, let go of your nose and breathe in only through the nose.

  7. Continue walking while recovering your breathing for 12 to 18 breaths (~1 minute).

  8. Repeat five times (or for 10-15 minutes).

  9. Aim to increase your breath hold step count with each subsequent round.

Important note:

  • For people with extreme anxiety or those prone to severe panic attacks, breath holding can be a trigger, so listen to your body and build up slowly or stick to exercise 1

  • Strong breath holds should not be practiced by those with serious medical conditions or if you are pregnant or looking to conceive


Fear and it’s associated panic and anxiety disorders are highly complex and everyone’s psychology and physiology is different. I am in no way suggesting that improving carbon dioxide tolerance is the be all and end all treatment for these problems. My aim with this article is to show that fear and anxiety can also manifest physically and that they are not just mental problems, where often the only treatment is asking someone to think differently.

Personally, I have been more helped with my mental health through improving my physiology than by any psychological therapy. It’s why I am passionate about sharing the benefits improved breathing can have on our lives.



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