No matter where you turn today, someone is talking about the vagus nerve. Podcasts, books, self-help guides, Facebook and Instagram accounts are all devoted to it.
The vagus nerve is the longest cranial nerve in the body, running from the brainstem through the neck and chest and into the abdomen. It is often described as the physical structure behind the mind-body connection. In Latin, the word ‘vagus’ means wandering, which is a fitting name; it literally wanders through the body rather than following a single, direct path.
You may have come across the term ‘gut-brain axis’ in your reading or listening, and this is where research has flipped the traditional narrative. Most people assume that signals flow from the control centre, the brain, down the gut. In reality, approximately 80% of vagus nerve fibres carry signals in the opposite direction, from the gut up to the brain.¹ This is why gut health has such a direct influence on mood, anxiety and cognitive function: the gut is constantly sending messages to the brain via the vagus nerve, and this is the gut-brain axis in action.
The messages relayed to the brain cover things like current levels of inflammation, the state of the gut microbiome, nutrient levels and how digestion is progressing. These messages are relayed to the parts of the brain which regulate mood, appetite and the stress response.
Vagal tone refers to how responsive the vagus nerve is and determines how well the parasympathetic nervous system (PNS, the 'rest and digest' state) can override the sympathetic nervous system (SNS, the 'fight or flight' state). Higher vagal tone tends to mean faster recovery from stress, better emotional regulation and stronger heart rate variability, or HRV. Lower vagal tone tends to mean slower recovery from stress, heightened reactivity and slower HRV.² Many wearable devices now make it possible to track your own vagal tone via HRV.
When vagal tone is good, this typically shows up as resilience, emotional stability and quick recovery from stressful situations. When it's poor, it tends to show up as feeling easily overwhelmed, physically tense, sleeping badly and taking longer to recover once stress hits. This is part of the mechanism behind the phrase 'wired but tired', where the off switch simply isn't working as well as it should.
This same recovery mechanism is also what governs your ability to fall into a deep sleep.
Low vagal tone keeps the body in a mild state of alert, which robs you of the deep, restorative sleep that leaves you feeling refreshed on waking. Improving vagal tone is one of the less talked-about but genuinely effective ways to improve sleep quality, particularly for people whose sleep problems stem from an inability to switch off.
Of the nutrients studied in relation to vagal tone, Omega 3 has the most evidence behind it. It contains EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), both of which have anti-inflammatory effects and directly support vagus nerve function. Omega 3 is described as the best nutritional intervention for enhancing vagal tone, with consistent supporting evidence, and a meta-analysis of 51 RCTs found that Omega-3 significantly decreased resting heart rate, consistent with enhanced vagal tone. Higher omega 3 intake is also associated with higher HRV (a recognised marker of vagal tone).³˒⁴
Probiotics are also an emerging area of interest here. Certain probiotic strains have been found to communicate with the brain via the vagus nerve, and some have been shown in animal studies to modulate vagal activity and influence anxiety-related behaviour, with human data still developing.⁵˒⁶
Magnesium plays a role too, since it’s essential for the neurotransmitter systems involved in regulating the parasympathetic nervous system, including acetylcholine, which the vagus nerve uses directly. Small human trials have linked magnesium supplementation to improved HRV, though the evidence here isn't as robust as it is for the omega 3.
Zinc plays a broader role in nervous system health and nerve conduction, but its specific relationship to vagal tone hasn’t been directly studied.
Slow, paced breathing, at around 6 breaths per minute, is one of the most consistently evidence-based ways to increase vagal tone. Many people find that extending the exhale is helpful, although research on whether the ratio matters is mixed.⁷˒⁸
Even a brief splash of cold water on the face activates what is known as the diving reflex, a response mediated by the vagus nerve. This is well documented to slow the heart rate and shift the body towards parasympathetic dominance.⁹
Humming and singing may also stimulate vagus nerve fibres by creating vibration in the larynx, through which the vagus nerve passes. Some small studies have found this produces a calming, HRV-boosting effect, with slow, rhythmic vocalisation such as chanting appearing to be the most effective form.¹⁰
The reason that the vagus nerve has captured so much attention recently isn’t because that it's the next wellness trend but that this 'wandering nerve' turns out to be one of the few parts of our physiology that we can directly influence. Breath, nutrition and simple daily habits provide a starting point for how your body handles stress, sleep and recovery.
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You may also enjoy reading:
1. Bonaz B, Bazin T, Pellissier S. (2018) The Vagus Nerve at the Interface of the Microbiota-Gut-Brain Axis. Front Neurosci.12:49.https://pmc.ncbi.nlm.nih.gov/articles/PMC5808284/
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