What is the vagus nerve?

The vagus nerve is the longest cranial nerve, running from the brainstem down through the neck and chest to the abdomen, connecting the brain with the heart, lungs, and digestive tract. It is the main highway of the parasympathetic “rest-and-digest” nervous system and a central channel of the gut–brain axis.

What does the vagus nerve do for digestion?

The vagus nerve drives “rest-and-digest” activity: it stimulates stomach acid and digestive enzymes, controls gut muscle movement (motility), and carries sensory information from the gut back to the brain. Most of its fibers are sensory — meaning the gut sends far more signals up to the brain than the brain sends down.

How can I stimulate my vagus nerve naturally?

Evidence-supported approaches include slow deep breathing (especially long exhales), humming or singing, cold exposure, gentle exercise, meditation, and good sleep. These activate the parasympathetic response and can raise vagal tone over time.

VAGUS NERVE

The Vagus Nerve: The Gut–Brain Superhighway

Q: What is vagal tone and why does it matter?

Vagal tone is a measure of how active your vagus nerve is, often estimated through heart rate variability (HRV). Higher vagal tone is associated with better stress resilience, calmer digestion, and faster recovery, while low vagal tone is linked to stress, inflammation, and digestive issues.

By The Scora Science Team · June 26, 2026 · Updated June 26, 2026

TL;DR

The vagus nerve is the longest cranial nerve and the main line of the gut–brain axis. It runs the body’s ‘rest-and-digest’ mode, and most of its fibers carry signals from gut to brain. Higher vagal tone (seen via HRV) is linked to calmer digestion and better stress resilience.

The vagus nerve is the longest of the cranial nerves — a wandering cable (its name means “wandering”) that runs from your brainstem down through the neck and chest into the abdomen, linking the brain with the heart, lungs, and gut. It is the principal channel of the gut–brain axis and the backbone of your “rest-and-digest” nervous system.

Mostly a listening line

Here is the surprise: roughly 80% of the vagus nerve’s fibers are sensory — they carry information from the body to the brain. In other words, your gut sends far more signals up than your brain sends down. Your body is constantly reporting its internal state, and the vagus nerve is the wire it uses.

What it does for your gut

Triggers stomach acid and digestive enzymes
Controls motility — the muscle movements that move food along
Calms inflammation through the “inflammatory reflex”
Relays gut sensations — fullness, discomfort — to the brain

Vagal tone and HRV

Vagal tone describes how active your vagus nerve is. Because the vagus influences your heartbeat, it can be estimated through heart rate variability (HRV) — the small beat-to-beat timing changes in your pulse. Higher vagal tone is associated with better stress resilience, smoother digestion, and quicker recovery; low vagal tone tracks with stress and inflammation.

How to support your vagus nerve

Breathe slowly, with long exhales (e.g. 4 in, 6–8 out).
Hum, chant, or sing — the vagus connects to the vocal cords.
Try brief cold exposure, like a cold splash or end-of-shower cool down.
Move gently and meditate, and protect your sleep.

The bigger picture

The vagus nerve is why a nervous stomach and a calm mind are two sides of one system. It is also a reminder that the gut is always sending signals — we just rarely have a way to read them. Scora is building one. Join the waitlist or read the science.

Educational content, not medical advice. Consult a qualified professional for health concerns.