Ready to begin or deepen your meditation practice? Join Dan Harris and world-class meditation teachers on the 10% with Dan Harris app here: https://app.danharris.com/membership The vagus nerve is all over social media right now — and most of what you're reading is either oversimplified, unproven, or someone trying to sell you something. This episode is the antidote. Dr. Kevin Tracey is a neuroscientist, physician, and president of the Feinstein Institutes for Medical Research. He is the scientist who discovered 25 years ago that the vagus nerve controls inflammation — a finding that has since led to FDA-approved implanted devices for treating rheumatoid arthritis. His new book is The Great Nerve: The New Science of the Vagus Nerve and How to Harness Its Healing Reflexes. In this conversation, Kevin and Dan cover: - What the vagus nerve actually is — and why Kevin prefers to call it "the great nerve" - Why vagal tone and heart rate variability are real but widely misunderstood — and what your wearable can and can't tell you - The honest evidence for breath work: what we know, what we don't, and why Kevin does it anyway (Pascal's wager) - The specific breathing technique Kevin uses daily: three seconds in, seven seconds out, six breath cycles per minute - What inflammation actually is — and why the vagus nerve is essentially the body's built-in brake on the immune system - The difference between acute inflammation (good) and chronic inflammation (the driver of heart disease, cancer, Alzheimer's, and more) - Cold exposure: the two anti-inflammatory mechanisms at work, why cold showers are safer than ice baths, and the diving reflex - Exercise and vagal tone: what the population data shows — and where the science gets murky - Bioelectronic medicine: the FDA-approved implanted device the size of a fish oil pill that treats rheumatoid arthritis by activating the vagus nerve for one minute a day - Vagus nerve stimulation for treatment-resistant depression: 50% of patients improve significantly — and why most insurance won't cover it - The honest verdict on ear stimulation devices: some intriguing clues, a lot of marketing ahead of the evidence Subscribe to watch more 10% Happier videos: https://www.youtube.com/tenpercenthappier Follow Dan Harris on Social Media: https://www.instagram.com/danharris/ https://www.tiktok.com/@danbharris https://www.facebook.com/DanHarrisABC https://twitter.com/danbharris https://www.linkedin.com/in/dan-harris-91ba5716b/ Timestamps: 0:00:00 What is the vagus nerve? The basics 0:02:00 Why Kevin prefers "the great nerve" — and what Galen got right 2,000 years ago 0:04:00 Why you should care: the vagus nerve as the body's command center 0:07:00 Why the vagus nerve is having a cultural moment right now 0:09:00 Vagal tone — what it means and why you have to be careful with the term 0:14:00 Heart rate variability — what it is and what your wearable can't tell you 0:20:00 What we can actually do: Grandma was right 0:24:00 The breathing technique Kevin does daily: three in, seven out 0:28:00 What inflammation is — redness, pain, swelling, heat, and the molecules behind it 0:30:00 The discovery: the vagus nerve as the body's built-in brake on inflammation 0:32:00 Acute inflammation (necessary) vs. chronic inflammation (dangerous) 0:34:00 Does breath work reduce inflammation? What the evidence actually shows 0:38:00 Dan's straw breathing practice; separating breath work from meditation 0:44:00 What meditation does to the brain — and its overlap with vagus nerve stimulation 0:50:00 Cold exposure: two anti-inflammatory mechanisms and the limits of the evidence 0:55:00 Kevin's cold shower routine; the diving reflex; splashing cold water on your face 1:01:00 Saunas; heart rate recovery as an indicator of vagal tone 1:03:00 Exercise: overwhelming population evidence, murkier HRV data 1:06:00 What is bioelectronic medicine? 1:08:00 The Setpoint Medical device: FDA-approved, the size of a fish oil pill, one minute a day 1:11:00 Vagus nerve stimulation for depression and epilepsy — why 50% respond and 50% don't 1:14:00 Dan's depression; could someone get a device implanted? 1:17:00 Generation one vs. generation two devices; stroke recovery applications 1:20:00 Ear stimulation devices — some real science, a lot of hype 1:24:00 Where bioelectronic medicine is headed #neuroscience #mentalhealth #inflammation This episode is sponsored by: BetterHelp — Online therapy, matched to your needs. Get 10% off your first month at https://www.betterhelp.com/happier Spark — Clean energy and focus with zero sugar. Get 30% off and free shipping with code HAPPIER at https://www.drinkspark.com