What exactly is the vagus nerve?
The vagus nerve is the longest cranial nerve in the body. It originates in the brainstem and travels down through the neck, chest, and abdomen, branching into the heart, lungs, esophagus, stomach, liver, kidneys, and intestines. The word "vagus" comes from the Latin for wandering — and it does wander, connecting more organs than any other nerve in the body.
It is the primary nerve of the parasympathetic nervous system — the system that governs rest, digestion, immune function, and recovery. When the vagus nerve is active and well-toned, the body can shift out of stress and into restoration. When vagal tone is low, the nervous system tends to stay stuck in a state of alert.
Why does everyone seem to be talking about the vagus nerve right now?
Because chronic stress has become the default state for many people, and the vagus nerve is the most direct pathway out of it. Research over the past two decades has shown that vagal tone — the activity level of the vagus nerve — is one of the most reliable predictors of stress resilience, emotional regulation, and physical health. Higher vagal tone correlates with better heart rate variability, calmer digestion, stronger immune function, and greater capacity to recover from difficult experiences.
The good news is that vagal tone is not fixed. It responds to practice.
How does Iyengar yoga affect the vagus nerve?
Several elements of Iyengar yoga directly stimulate the vagus nerve — not as a side effect, but as a structural feature of the practice:
Extended Exhale
Slow, extended exhalation directly activates the parasympathetic system via the vagus nerve. Ujjayi breath and Nadi Shodhana pranayama both lengthen the exhale. Light on Pranayama describes these as calming and purifying practices.
Sarvangasana & Viparita Karani
Inversions stimulate the baroreceptors in the neck and chest — pressure sensors that signal safety to the nervous system and increase vagal tone. B.K.S. Iyengar called Sarvangasana the "queen of asanas" for its systemic regulatory effects.
Paschimottanasana
Forward folds quiet the nervous system by compressing the abdomen and stimulating the vagal branches that run through the gut. Prescribed in Path to Holistic Health for nervous system regulation and stress recovery.
Sustained Inner Focus
The quality of attention required by Iyengar practice — precise, sustained, non-reactive — trains the prefrontal cortex to regulate the stress response. This top-down regulation directly supports vagal function over time.
"The practice of yoga is not about the body alone. It is about learning to inhabit the body with intelligence — and that intelligence begins with the breath." — B.K.S. Iyengar, Light on Life
What does low vagal tone feel like?
Low vagal tone does not always announce itself clearly. It tends to show up as a collection of symptoms that are easy to attribute to other causes: difficulty recovering from stress, digestive irregularity, poor sleep quality, a sense of being "wired but tired," chronic tension in the shoulders and jaw, and a nervous system that seems to stay on alert even when nothing is wrong.
In the March 2026 Be Aligned newsletter, the reflection was about protecting the nervous system — not as a luxury but as a necessity. The language of the vagus nerve was not used, but the practice described was exactly this: anchoring the body, slowing the breath, reducing stimulation, staying connected to the people in front of you. These are all vagal toning practices.
What are the most practical ways to support vagal tone?
The most evidence-supported approaches are also the most accessible: slow diaphragmatic breathing with a longer exhale than inhale; cold water on the face or a cold shower; humming, singing, or chanting; social connection with people you feel safe with; and consistent yoga practice — particularly practices that emphasize breath regulation and parasympathetic activation. Iyengar yoga incorporates several of these simultaneously.