What does the vagus nerve do?

The vagus nerve has become one of the most searched-for parts of the body, and for good reason. It connects your brain to many of your vital organs and plays a central role in how your body rests, recovers and digests. Here is what the science says.

Where the vagus nerve runs

The vagus nerve is the tenth cranial nerve and the longest of them all. It starts in the brainstem, leaves the skull, travels down the neck and branches throughout the chest and abdomen [1]. Its name comes from the Latin for “wandering”, which suits its long route through the body.

What it does

The vagus nerve carries signals that help control [1]:

• Heart rate: it helps slow and steady the heartbeat.
• Breathing: it supplies the airways and lungs.
• Digestion: it provides movement and sensation to the gut.
• Swallowing and voice: it controls muscles in the throat and voice box.

It is the main nerve of the parasympathetic nervous system, the “rest and digest” side of your automatic nervous system [2]. Around 80% of its fibres carry information from the body up to the brain, so much of its job is listening to how your organs are doing [2].

What is vagal tone?

“Vagal tone” describes how active the vagus nerve is. It cannot be measured directly in everyday life, so researchers often use heart rate variability, the natural beat-to-beat variation in your heart rhythm, as an indicator [3].

Can breathing influence it?

A systematic review of 15 studies in healthy adults looked at slow breathing, at fewer than 10 breaths per minute. Slow breathing consistently increased heart rate variability and other signs of parasympathetic activity. Participants also reported feeling more relaxed and less anxious [3]. Slow, steady breathing is free, simple and something anyone can try.

What is vagus nerve stimulation?

Vagus nerve stimulation uses gentle electrical signals to stimulate the nerve. Implanted stimulators have been used in epilepsy care for more than 20 years [4]. Non-invasive approaches work through the skin at the neck or ear, with no surgery, and NICE recommends one such device for cluster headache [5]. A 2022 review of ear-based stimulation studies found that side effects were generally mild and short-lived, most often ear discomfort, headache or tingling [6]. Researchers are studying stimulation for a range of other uses [1].

If you have symptoms that concern you, speak to your GP before trying any device.

At CortiAura, we are developing new non-invasive technology built around the gut–brain connection. Join our Founding Community to follow our progress.

References

1. StatPearls, US National Library of Medicine. Neuroanatomy, Cranial Nerve 10 (Vagus Nerve).
2. Bonaz B, Bazin T, Pellissier S. The vagus nerve at the interface of the microbiota–gut–brain axis. Frontiers in Neuroscience 2018;12:49.
3. Zaccaro A, Piarulli A, Laurino M, et al. How breath-control can change your life: a systematic review on psycho-physiological correlates of slow breathing. Frontiers in Human Neuroscience 2018;12:353.
4. NICE. Vagus nerve stimulation for refractory epilepsy in children (IPG50), 2004.
5. NICE. gammaCore for cluster headache (MTG46), 2019.
6. Kim AY, Marduy A, de Melo PS, et al. Safety of transcutaneous auricular vagus nerve stimulation (taVNS): a systematic review and meta-analysis. Scientific Reports 2022;12:22055.