The Vagus Nerve Explained: Mind-Body Science for Mental Health and Resilience
Disclaimer: This blog is intended for informational and educational purposes only and should not be considered medical advice. It is not a substitute for professional diagnosis, treatment, or guidance.
What is the Vagus Nerve?
The vagus nerve (cranial nerve 10) is one of the most extensive and complex nerves in the body.
This nerve plays a vital role in alertness, calm, digestion, immune response, and even learning. Importantly, its diverse effects depend on which specific branches are activated—contrary to the popular belief that it only promotes relaxation.
It connects the brainstem to nearly every major organ system, including the heart, lungs, gut, liver, pancreas, and spleen. It not only sends information from the body to the brain (like heart rate, digestion, and internal comfort) but also transmits signals from the brain back to the body to regulate functions like breathing, digestion, and organ movement.
It’s named “vagus” (Latin for “wandering”) because of its widespread reach throughout the body.
Sensory vs. Motor Functions
The vagus nerve is a mixed nerve, meaning it contains both sensory (afferent) and motor (efferent) neurons.
About 85% of vagus nerve fibers are sensory, carrying information from the body to the brain.
These fibers detect mechanical (e.g. stretch, pressure) and chemical (e.g. pH, neurotransmitters like serotonin) changes in organs.
The other 15% are motor fibers, sending signals from the brain to control organ function, such as heart rate or digestive activity.
Structure of Sensory Neurons
Many vagus sensory neurons are bipolar — they have:
One branch going to an organ (like the gut or lungs),
Another branch going to the brainstem.
These neurons collect and send real-time data about the body’s internal state to the brain.
Importance of Sensory Input
The vagus nerve helps the brain regulate:
Mood
Alertness or relaxation
Immune response
Learning and memory
For example, gut serotonin levels (90% of which is made in the gut) affect brain serotonin and mood — this info travels via the vagus nerve.
Mechanical vs. Chemical Information
Mechanical input: Sensed by stretch receptors (e.g. a full stomach or deep breathing).
Chemical input: Detected through chemoreceptors (e.g. acidity or neurotransmitter levels).
Both are critical for regulating the body’s internal balance (homeostasis).
Autonomic Nervous System Balance
The autonomic nervous system includes:
The sympathetic system (alertness, fight-or-flight).
The parasympathetic system (relaxation, digestion).
The vagus nerve influences both, depending on which branch is activated.
Parasympathetic Role & Misconceptions
The vagus nerve is part of the parasympathetic nervous system (rest and digest).
However, activating the vagus nerve doesn’t always mean calming down.
Some branches promote relaxation (e.g. gentle ear rubbing).
Others can actually increase alertness.
Context and specific branch activation matter.
The Summary So Far..
The vagus nerve plays a central role in mind-body communication.
It can be leveraged for practical outcomes like mood improvement, better focus, or faster relaxation — but different branches do different things.
Understanding which type of information (chemical or mechanical) you’re influencing is crucial to using vagus-based tools effectively.
Leveraging the Vagus Nerve for Health, Performance, and Longevity
The vagus nerve plays a critical role in autoregulation—the body’s ability to balance the sympathetic (alert, stress) and parasympathetic (calm, recovery) nervous systems. This regulation is crucial not only for mental and physical health, but also for performance, recovery from illness, and healthy aging.
A core function of the vagus nerve is to decelerate heart rate through a pathway from the left dorsolateral prefrontal cortex → brainstem (nucleus ambiguus) → sinoatrial node of the heart. This slows the heart and increases heart rate variability (HRV)—a marker of good health, resilience, and recovery.
Key Tools
You can consciously activate this calming vagal pathway:
Extended Exhales: Simply slowing down your exhale activates parasympathetic control, lowering heart rate and increasing HRV.
These techniques echo practices from yoga and breath work but are explained here with a neurobiological perspective.
Physiological Sigh: A fast, powerful calming technique: (https://www.youtube.com/watch?app=desktop&v=kSZKIupBUuc)
Two quick inhales through the nose
One long, slow exhale through the mouth
This instantly reduces stress by shifting your nervous system into a calm state—mechanically and chemically
Neck Stretch & Head Turn
Mechanically stimulating vagus nerve fibers by pushing elbows down, turning the head up and to each side.
This stretches neck muscles and stimulates vagus nerve branches, promoting calmness.
Though less potent than electrical vagus nerve stimulation used clinically, it’s a simple, supported method.
Gentle stimulation behind or inside the ear activates a sensory branch of the vagus nerve, promoting a mild calming effect.
However, it’s not a powerful tool for serious stress or anxiety
Extended Humming
Humming activates vagus nerve fibers in the throat via vibration.
The key is to emphasize the “H” sound (an extended breathy exhale) rather than the “M” sound.
This vibrational stimulation calms the nervous system by engaging parasympathetic pathways.
The sensation is similar to gargling and can be felt moving down the throat into chest and abdomen.
Singers use this technique to relax and access deeper vocal tones.
**By intentionally using these exercises, you can train your body to regulate stress more effectively** Many more under the sun, I encourage you to find what works for you
Why the Tools matter
Practicing this throughout the day (10–20 times) strengthens the neural pathway through neuroplasticity, leading to more effective background (automatic) regulation—even while you sleep.
HRV (Heart Rate Variability) tends to decline with age, partly due to brain atrophy (especially in the prefrontal cortex). Deliberate practice or tools like transcranial magnetic stimulation can keep this system strong.
Higher HRV is associated with better cognitive performance, mood, cardiovascular health, and longevity.
Deliberately slowing down your exhale just 10–20 times per day can significantly improve your health and resilience. Each extended exhale activates a calming vagus nerve pathway—from the brain to the heart—that lowers your heart rate and boosts (HRV), a key marker of physical and emotional well-being.
The more often you do this, the stronger this calming circuit becomes—thanks to neuroplasticity. Over time, it starts working automatically, even during sleep. This easy, low-effort habit can be practiced anytime during the day, helping you feel calmer in the moment while also supporting long-term stress regulation and overall health.
How to Use Movement to Boost Alertness Through the Vagus Nerve
Although the vagus nerve is known for promoting calm (“rest and digest”), it also plays a role in increasing alertness and motivation—especially during physical activity.
When you move large muscle groups your adrenal glands release adrenaline. While adrenaline doesn’t enter the brain, it binds to receptors on the vagus nerve. This triggers a chain reaction:
Vagus nerve activates the nucleus tractus solitarius (NTS).
NTS activates the locus coeruleus, which releases norepinephrine across the brain.
This increases brain alertness, focus, and motivation.
This means that even if you’re feeling tired or unmotivated, just starting to move your body—especially with intense or resistance-based exercise—can wake up your brain and boost energy. It’s a natural alternative to stimulants like caffeine and works fast.
Understanding and using this pathway gives you control over your mental and physical state, helping overcome brain fog, lethargy, and low motivation.
Alertness & Adult Neuroplasticity
The vagus nerve doesn’t just calm the body—it also plays a crucial role in increasing alertness and enabling adult learning (neuroplasticity).
As adults, we can’t passively absorb learning like children do. Instead, we need:
Alertness
Focus
Repetition over time (incremental learning)
Sleep, which is when the actual brain rewiring happens.
Two key brain chemicals enable this:
Norepinephrine from the locus coeruleus boosts alertness.
Acetylcholine from nucleus basalis enhances focus and opens the window for plasticity.
High-intensity physical exercise, especially involving large muscles, triggers a vagus nerve pathway that:
Stimulates the adrenal glands to release adrenaline
Activates the brain’s alertness and focus circuits (locus coeruleus & nucleus basalis)
Creates an optimal state for learning in the hours after exercise
This process can be amplified with tools like caffeine or (cautiously) nicotine or supplements like Alpha GPC, though exercise alone is a powerful method.
Proper sleep after learning is essential for actual brain changes to occur.
Bottom line: To boost learning and brain plasticity as an adult, engage in short, intense bouts of exercise before focused learning sessions. This harnesses your vagus nerve and primes your brain for change—no stimulants required.
Gut Health & the Vagus Nerve (Focus on Serotonin and Depression)
SSRIs & Depression
SSRIs (Selective Serotonin Reuptake Inhibitors) increase serotonin in the brain and are commonly used to treat depression.
Their effectiveness varies: some people benefit, others experience significant side effects because serotonin affects many brain systems.
SSRIs may help by increasing neuroplasticity, allowing people with depression to learn new, more positive thought patterns.
However, serotonin is not the only factor in depression, and SSRIs aren’t a universal solution.
Serotonin in the Gut & Brain
90% of the body’s serotonin is made in the gut, but it doesn’t travel to the brain.
Instead, the vagus nerve detects gut serotonin and signals the brain to release more serotonin from the dorsal raphe nucleus.
This gut-brain loop is critical for mood regulation and overall mental well-being.
Boosting Serotonin Naturally
To enhance gut serotonin (and thus brain serotonin), focus on:
Gut microbiome health:
Eat 1–4 servings daily of low-sugar fermented foods (e.g., kimchi, sauerkraut, kefir, plain yogurt, refrigerated pickles).
These support the growth of gut bacteria that produce short-chain fatty acids, needed to convert tryptophan into serotonin.
Adequate tryptophan intake:
Tryptophan (an amino acid) is the raw material for serotonin.
Found in foods like turkey, dairy, eggs, and some seeds.
Gut bacteria and enzymes convert tryptophan into serotonin if the gut environment is healthy.
Occasional probiotics:
Can support gut health and mood, but should not be overused.
A short clinical trial showed that a combo of probiotics + magnesium orotate + CoQ10 reduced depression symptoms in the short term.
This combo significantly reduced depressive symptoms by week 4, with some maintained benefit in mood and stress even beyond the treatment period. However, the long-term efficacy (post-treatment) did not persist robustly.
Key Mechanism
Healthy gut → more serotonin in gut → vagus nerve senses it → brain releases serotonin → improved mood & neuroplasticity.
Bottom Line:
A healthy gut supports a healthy brain. By improving gut microbiota through fermented foods and getting enough tryptophan, you naturally promote serotonin balance and support mood, motivation, and neuroplasticity—all via the vagus nerve.
Summary: Practical Takeaways
The vagus nerve is an amazingly complex and versatile neural circuit that controls many bodily functions, from sensory input to motor output.
It plays a crucial role in calming the body, regulating alertness, linking gut serotonin (influenced by diet and microbiome) to brain serotonin, mood, learning, and neuroplasticity.
While some yogic and retreat practices for calming the vagus nerve have scientific support, the nerve’s full range of functions is still being explored.
Advanced techniques like electrical or magnetic stimulation of the vagus or related brain areas require medical devices and professionals.
This discussion focused on practical, accessible ways anyone can engage their vagus nerve for better mental and physical health.
The vagus nerve is active throughout life, from birth to old age, and understanding how to control it biologically gives us more power over our well-being.
Disclaimer: This blog is intended for informational and educational purposes only and should not be considered medical advice. It is not a substitute for professional diagnosis, treatment, or guidance.
