Your Autonomic Nervous System
How to become its Master
In my previous post (13/5/25) “How you got here”, I discussed the relationship between bottom>up (limbic/amygdala>prefrontal cortex) / top>down (prefrontal cortex >limbic/amygdala) brain action, adaptive vs maladaptive brain plasticity, and the Window of Tolerance; and that when we are stressed/anxious, the limbic/amygdala activity over-powers the pre-frontal cortex (PFC), significantly reducing our ability to reason and think logically.
Fundamentally, a return to a natural Window of Tolerance is reliant on achieving re-balance between limbic/amygdala and prefrontal cortex (PFC) activity of the Autonomic Nervous System.
Here is a diagram representation of the Nervous System, its many component parts and the Autonomic Nervous System (ANS) indicated by the red arrow:
There are strong links between tinnitus intrusiveness and loudness perception, and arousal (stress and anxiety). Arousal is the term used for Sympathetic Nervous System activity, consisting higher than normal levels of neurotransmitters (chemicals and hormones) including adrenaline and cortisol (see HPA Axis below).
How do you even BEGIN to bring about the necessary “re-balancing” when your ability to reason and think logically is inhibited?
Indeed, the harder you try to “think through what is happening to you” in an attempt to solve the predicament because you want some certainty over uncertainty, the more UN-certain, fearful, anxious and stressed you are likely to feel, and the more intrusive and loud the tinnitus is perceived to be.
Here’s how…
There is a need to regulate what has become a dysregulated nervous system, specifically by re-regulating the Hypothalamic-Pituitary-Adrenal Axis (HPA Axis)
Regulating a dysregulated nervous system (re-balancing) has to be undertaken in stages.
Just as your Window of Tolerance didn’t suddenly shrink – your Autonomic Nervous System (ANS) via the HPA Axis didn’t suddenly become dysregulated/imbalanced. These changes have occurred over time, not suddenly, not overnight.
The Goal
Ultimately, we are aiming to free-up the prefrontal cortex (PFC) so it can return to keeping the amygdala in check, thus calming limbic activity. It is done broadly in two stages:
Physically activate the suppressed parasympathetic nervous system (PNS) to begin lowering hyperactivity in sympathetic nervous system (SNS). This draws the two counter-activities closer together
Once PNS and SNS activities draw closer together, the PFC increases its capacity for reason and logic. This renewed PFC capacity is now able to begin to redress anxiety and stress provoking automatic-negative-thoughts.
The second stage (2) is achieved through Cognitive Therapy. For now, we are focusing on (1):
How to physically activate the suppressed parasympathetic nervous system (PNS) to begin lowering hyperactivity in sympathetic nervous system (SNS)
The limbic system – including the amygdala – cannot be communicated with through talking to it! The limbic system is “non-verbal”.
Interaction with the limbic system is “communicated” at the physiological level; it is our emotional centre. When we are stressed and/or anxious, SNS activity increases. Increased SNS activity (stress/anxiety) suppresses (disengages) PNS activity (rest/digest).
Mastering your Autonomic Nervous System
The most effective way to re-engage parasympathetic activity (PNS) is through the practice of regular and consistent breathing and relaxation exercises, building up their ROUTINE use starting with “little and often”. The routine is as important as the exercises themselves, because routine = dependable, and dependable = safe.
All the detail of what the specific exercises are, how often to do them, what they do, establishing a routine - how and why - etc is laid out throughout the CBT4T programme.
Dipping a toe in to Artificial Intelligence (AI)
AI is not something I have previously “embraced”… I don’t understand it, I’ve never used it, and I freely admit, I don’t trust it!
However, I had this article in the planning, and a few days ago, the idea popped in to my mind to “test it out”. Asking a question about something I already know the answer to seemed like a good idea… I am glad I did too - see my verdict at the end!
Asking Grok
First, I used Grok – my question: “What do breathing exercises do to the human nervous system?”
Well, to say I was impressed is an understatement! Here is Grok’s answer (in italics to differentiate from my own content):
[Start Grok] “Breathing exercises influence the human nervous system by modulating the autonomic nervous system (ANS), which regulates involuntary functions like heart rate, blood pressure, and digestion. The ANS has two main branches: the sympathetic nervous system (SNS), which activates the "fight or flight" response, and the parasympathetic nervous system (PNS), which promotes "rest and digest." Breathing exercises primarily enhance PNS activity, leading to relaxation and reduced stress, while also affecting brain function and emotional regulation.
Here’s a detailed breakdown:
1. **Activation of the Parasympathetic Nervous System**:
- Slow, deep breathing (e.g., diaphragmatic or box breathing) stimulates the vagus nerve, a key PNS component. This increases acetylcholine release, slowing heart rate and reducing blood pressure.
- Studies show that controlled breathing at 6–10 breaths per minute maximizes heart rate variability (HRV), a marker of PNS dominance, promoting relaxation and resilience to stress.
2. **Reduction of Sympathetic Activity**:
- Rapid, shallow breathing can trigger SNS activation, increasing cortisol and adrenaline. Conversely, deliberate slow breathing lowers SNS activity, reducing stress hormones.
- Research indicates that techniques like alternate nostril breathing decrease sympathetic markers, such as galvanic skin response, in as little as 15 minutes.
3. **Impact on Brain Function**:
- Breathing exercises alter brainwave patterns, increasing alpha waves (associated with relaxation) and reducing beta waves (linked to alertness/stress). EEG studies show this shift during practices like mindfulness-based breathing.
- They enhance activity in the prefrontal cortex, improving emotional regulation and decision-making, while reducing amygdala activity, which drives fear and anxiety responses.
4. **Regulation of the Hypothalamic-Pituitary-Adrenal (HPA) Axis**:
- Slow breathing reduces cortisol release by calming the HPA axis, the body’s stress response system. This helps mitigate chronic stress effects like inflammation and immune suppression.
- A 2018 study found that 20 minutes of daily breathing exercises lowered cortisol levels significantly over 8 weeks.
5. **Improved Oxygenation and CO2 Balance**:
- Controlled breathing optimizes oxygen delivery and carbon dioxide expulsion, stabilizing blood pH. This reduces physiological stress signals that could activate the SNS.
- Techniques like coherent breathing align respiratory and cardiovascular rhythms, enhancing autonomic balance.
6. **Neuroplasticity and Long-Term Effects**:
- Regular practice of breathing exercises can rewire neural pathways, strengthening connections between the prefrontal cortex and limbic system. This enhances emotional resilience over time.
- Longitudinal studies suggest that consistent practice (e.g., 10–20 minutes daily for 12 weeks) increases vagal tone, improving stress recovery and mood stability.
**Practical Examples**:
- **Diaphragmatic Breathing**: Inhale deeply through the nose for 4 seconds, hold for 4, exhale for 6–8. This maximizes vagal stimulation.
- **4-7-8 Breathing**: Inhale for 4, hold for 7, exhale for 8. It rapidly reduces acute stress by boosting PNS activity.
- **Alternate Nostril Breathing**: Balances left and right brain hemispheres, reducing SNS activity and enhancing focus.
**Caveats**:
- Effects vary by individual and technique. For example, fast-paced breathing (e.g., Wim Hof method) may initially activate the SNS before inducing relaxation.
- People with respiratory or cardiovascular conditions should consult a doctor before starting.
- Overdoing certain techniques (e.g., hyperventilation) can cause dizziness or alkalosis, disrupting nervous system balance.
In summary, breathing exercises shift the nervous system toward parasympathetic dominance, reduce stress, and enhance emotional and physiological regulation. Regular practice amplifies these benefits, making them a powerful tool for nervous system health. If you want specific techniques or a demonstration, let me know!” [End Grok]
ChatGPT answer to the same question
I then went to ChatGPT and decided to include it here too: My question: “What do breathing exercises do to the human nervous system?” (ChatGPT answer in italics)
[Start ChatGPT] “Breathing exercises have a significant and well-documented impact on the human nervous system. Here's a breakdown of what they do:
1. Activate the Parasympathetic Nervous System (PNS)
Mechanism: Slow, deep breathing—especially exhalation—stimulates the vagus nerve, which is a key part of the PNS.
Effects:
Slows heart rate
Lowers blood pressure
Promotes relaxation and recovery
Reduces stress hormones (like cortisol)
2. Regulate the Autonomic Nervous System (ANS)
The ANS controls involuntary functions like heart rate, digestion, and respiration.
Breathing is unique because it's both involuntary and voluntary—this makes it a powerful tool to consciously influence autonomic function.
Controlled breathing can shift the balance from sympathetic (fight or flight) dominance to parasympathetic (rest and digest) tone.
3. Improve Heart Rate Variability (HRV)
HRV is a measure of the variation in time between heartbeats, and it reflects nervous system balance.
Higher HRV is associated with better stress resilience and cardiovascular health.
Breathing exercises (especially coherent breathing at ~5-6 breaths/min) help improve HRV.
4. Reduce Sympathetic Nervous System Overactivity
In stressful situations, the sympathetic system ramps up—raising heart rate, tightening muscles, increasing alertness.
Chronic overactivation is linked to anxiety, hypertension, and burnout.
Breathing exercises help dampen this overactivity, calming the body and mind.
5. Enhance Emotional Regulation and Focus
By calming the nervous system, breathing exercises reduce amygdala reactivity (linked to fear and anxiety).
This leads to improved:
Emotional control
Cognitive clarity
Decision-making under stress
Summary Table
If you're interested, I can suggest specific breathing techniques like box breathing, 4-7-8 breathing, or resonance breathing, each with unique nervous system effects.” [End ChatGPT]
My Verdict?
AI has saved me a lot of typing for this article! I take no issue with either of the explanations - other than one thing: I err on the side of caution regarding the use of “deep breathing” - instead, I advocate using “natural” breathing, albeit still from the diaphragm i.e. diaphragmatic/abdominal breathing, as opposed to shallow clavicular breathing.
When someone is highly stressed, and they attempt breathing exercises, breathing deeply CAN induce hyperventilation that, in turn, CAN lead to a panic attack. Natural diaphragmatic/abdominal breathing used attentively still engages the PNS, and as the person gains confidence in the exercise, the breath naturally becomes deeper given time. There is a short video (YouTube) included in the course notes where I explain how to use the breathing exercise.
Additionally, anyone who has been stressed over a lengthy period of time, has high levels of tension in their body - to the point where being tense has become their “normal”. This makes using a breathing exercise more difficult for them to do than it would otherwise be. Therefore, for a high proportion of people coming to the CBT4T programme, I advise they use the 9 minute physiological relaxation exercise (instructions are in the course notes) PRIOR to two or three of the 6 x daily two-to-two and a half minute breathing exercises. They can then usually forego the physiological relaxation after 2-4 weeks of use, and fully benefit from the breathing exercise.
There are further relaxation exercises throughout the CBT4T process, including a 6 part mini-course in Autogenic Relaxation starting from Stage 6. There are also four longer (30 minute) guided relaxation recordings - originally chosen by over 100 patients I worked with while I was in the NHS; they are introduced at various stages throughout the process. I am currently planning to record a variety of relaxation exercises - varying in type and length - to add to the collection!
I admit I will continue to be wary of using AI for anything I don’t already know or understand; however, this was indeed a promising “first time”!
I’ll be interested to hear from any reader about your experiences of using AI too! Being such a newbie to it, I’ll be interested to hear from you!
And do please let me know your thoughts about this Newsletter article by commenting below. I can see from the numbers of people reading my Newsletter articles so far there are lots of you reading them.
Next Planned Newsletter Article
The next intended Newsletter concerns the importance of using CBT4T programme at a pace that suits your individual needs and responsibilities.
However, if you have additional topics to suggest, or a question burning away in your mind, let me know in the Chat.
Additional links that may be of interest
To view the CBT4T full programme Outline - you can enrol here too: https://courses.tinnituseprogram.org/cbt4t-2025
To view CBT for Tinnitus Distress for Audiologists and Hearing Therapists https://courses.tinnituseprogram.org/cbt-for-tinnitus-distress
To view CBT for Tinnitus for Advisors & Support Workers (soon to be updated) https://courses.tinnituseprogram.org/tinnitus-advisors
22/5/25
A great Substack, as was the previous one. When the body and mind are on alert, you need ways to calm them down. The exercises in the CB4T program are exceptionally good for this task!