Vagal tone: definition and why it matters

Vagal tone is a measure of how strongly your vagus nerve can shift your heart rate between activation and calm. It’s estimated through heart-rate variability (HRV), since it can’t be measured directly. Higher vagal tone is linked to recovering from stress more quickly. Lower vagal tone is linked to staying activated, or shut down, longer after a stressful moment passes.

Where does the term vagal tone come from?

Psychophysiologist Stephen Porges proposed vagal tone as a marker of stress vulnerability in a 1992 paper in Pediatrics. He’d already spent years indexing it through the natural speeding and slowing of heart rate with each breath. He argued it could show how well an infant’s nervous system handled stress. The idea became a building block of his broader polyvagal theory. That theory links the vagus nerve to shifts between calm, fight-or-flight, and shutdown states.

How is vagal tone actually measured?

You can’t check vagal tone with a single test. Researchers estimate it using heart-rate variability, or HRV. That’s how much your heart rate speeds up as you inhale and slows as you exhale. A 2017 methods paper in Frontiers in Psychology notes that posture and breathing rate both shift HRV readings. So one reading isn’t a fixed score.

Consumer wearables add more noise. A 2024 study in Sensors compared Apple Watch to a Polar H10 chest-strap monitor. HRV readings differed by an average of 29%, typically reading lower. Treat a wearable’s daily number as a rough trend, not a diagnosis.

What does higher or lower vagal tone mean for you?

Higher vagal tone tends to track with bouncing back from stress faster. A 2014 study in PLOS ONE looked at this directly. People with more emotion-regulation difficulty took longer for their cardiac vagal activity to settle back down after a stressful task. People who regulated emotion more easily recovered faster.

In practice, vagal tone is one physiological piece of nervous system regulation. It’s less a lab score and more a measure of how fast your body finds its way back to baseline. It’s a general tendency, not a medical diagnosis. It shifts over weeks and years, not in a single bad day.

Can you actually raise your vagal tone?

To a modest degree. A 2025 review in Acta Neurologica Belgica looked at slow, paced breathing. Longer exhales than inhales reliably raised HRV in the short term. Gains tend to be gradual and modest, built through repeated practice rather than a single session.

Many people pair slow breathing with bilateral stimulation, the rhythmic left-right technique at the center of EMDR. Our review of how bilateral stimulation affects the nervous system covers that research. EmEase, a self-guided EMDR app, offers a guided version of bilateral stimulation at app.emease.com, so you can practice it on your own time for everyday stress.