The Science of Regulating Your Nervous System: What the Vagus Nerve Actually Does

On April 27, Dan Harris released an episode of 10% Happier with Dr. Kevin Tracey called "The Science of Regulating Your Nervous System."Tracey is the president and CEO of the Feinstein Institutes for Medical Research at Northwell Health, a neurosurgeon, and the author of The Great Nerve: The New Science of the Vagus Nerve and How to Harness Its Healing Reflexes.

Since that episode dropped, a lot of people have gone looking for the same thing: a way to feel less activated, less inflamed, less braced. If that is why you are here, welcome. What follows is the version of this conversation I have with clients who are preparing for or recovering from psychedelic experiences, where nervous system regulation is not a wellness accessory. It is the whole job.

What the vagus nerve actually is

The vagus nerve is a pair of nerves running from your brainstem down through your neck and chest into your abdomen. It is a network of more than 200,000 fibers connecting the brain to vital organs, and it regulates essential functions including heart rate, breathing, and immune responses. Vagus is Latin for wandering, which is a good description of where it goes. Here is the detail that reframes everything: roughly 80 percent of the signals the vagus nerve carries travel from the body up to the brain, not the other way around. It is less a control knob you turn and more a sensory cable reporting on the state of your body. Your brain is constantly reading that report and deciding, below the level of conscious thought, whether you are safe. That is why "nervous system regulation" is not really a technique. It is a conversation between your body and your brain, and most of the traffic runs upward.

The discovery that made this a real field

Tracey's contribution is not the breathing exercises. He discovered the inflammatory reflex, a neural circuit by which the vagus nerve regulates immune responses and inflammation, which became the scientific foundation for bioelectronic medicine. Stimulate the nerve, and it signals the spleen to turn down inflammatory proteins. If you want the technical version, the review he co-authored on manipulating the inflammatory reflex is open access. This is not theoretical. His research enabled the first FDA-approved bioelectronic medicine device for rheumatoid arthritis, approved in 2025, with Northwell performing the first implantation later that year. It is roughly the size of a jelly bean, implanted on the vagus nerve in the neck, and it fires for about 60 seconds a day. In its pivotal trial against a sham implant, about 35 percent of patients whose arthritis had not responded to standard medication improved. Hold that number in mind. A surgically implanted device, delivering precisely targeted electrical stimulation, helped about a third of a hard-to-treat population. That is genuinely important science. It is also nothing like humming in your car.

The part the internet gets wrong

The most striking thing about Tracey is how skeptical he is of the culture that has grown up around his own work. In an op-ed for Northwell, his argument is that scientists are only beginning to map what the vagus nerve fibers do, so when you are told to stimulate your vagus nerve with a deep breath or an ice bath, the right question is "Which of my vagus nerves?" Nobody knows. In the lab, researchers can selectively stimulate specific fibers to slow the heart or suppress cytokines. An ice bath is not selective. It activates countless vagal fibers and also lights up the nerves driving your fight-or-flight response.

This is the crux. Cold plunges, humming, neck tapping, and ear clips are not switches. What these practices can do, as this overview in The Conversation puts it, is indirectly influence vagal activity by signaling to your body that it is safe. Slow breathing with a long exhale lowers heart rate and promotes a calmer state. In some people the effect is obvious. In others it is minimal.

That is a much smaller claim than the one being sold to you, and it is also a more useful one.

What the evidence actually supports

Strip away the marketing and a short, boring, effective list remains. The best-studied approaches are slow breathing, exercise, sleep, and medically supervised vagus nerve stimulation. Slow controlled breathing is among the most researched methods in relation to stress regulation and vagal activity, with diaphragmatic breathing, prolonged exhalation, and rates around five to six breaths per minute being the relevant variables. The most sensible approach is not vagus nerve hacking but a lifestyle that supports the nervous system as a whole: adequate sleep, exercise, stress reduction, and social stability.

Notice what is on that list. Sleep. Movement. Social stability. The unglamorous infrastructure of a life. Not a gadget.

Why this matters more in psychedelic work than almost anywhere else

If you are reading this because you are preparing for a psychedelic experience, integrating one, or sitting with someone else through theirs, the vagus nerve conversation stops being abstract.

Psychedelics are sympathetically activating. Classic psychedelics reliably produce effects consistent with sympathetic activation: pupil dilation, increased heart rate and blood pressure, and elevated cortisol and epinephrine. A racing heart three hours in is not evidence that something has gone wrong. It is pharmacology. Knowing that in advance prevents a great deal of unnecessary panic, and panic is what turns a hard passage into a harmful one.

Your baseline before you dose appears to matter. Research on DMT has described a pattern of sympatho-vagal coactivation during peak states, and found that autonomic balance before dosing predicts the depth and emotional tone of the experience that follows. A 2026 review in Frontiers in Neuroscience treats this autonomic pathway as one of the genuinely active ingredients in psychedelic therapeutics. This is the physiological argument for everything integration coaches nag you about: sleep the week before, do not walk in from a fourteen-hour workday, do not dose to escape an acute crisis. You are setting the initial conditions.

Recovery is a parasympathetic process. The pattern researchers describe is an initial stress response followed by a recovery phase driven by parasympathetic activity, sometimes called vagal rebound. Emerging work suggests psychedelics may enhance vagal tone, with increased heart rate variability observed during and after experiences, which lines up with clinical reports of improved emotional regulation afterward. A separate line of research tracking heart rate dynamics under LSD, DMT, psilocybin, and ketamine found consistent increases in high-frequency HRV and heart rate entropy during the experience itself.

That effect is not automatic, and it is not permanent. The days after a session are when a nervous system is most available to learn something new about safety. What you do with that window is integration.

A practical protocol, minus the hype

‍In the two weeks before a session. Protect sleep aggressively. Keep moving. Practice a slow-breathing pattern daily, five to six breaths per minute, exhale longer than the inhale, for ten minutes. You are not charging a battery. You are building a familiar physiological state you can find again under pressure, which is the actual skill. During. If you are sitting for someone, remember that arousal is expected. Lower your own voice and slow your own breathing before you intervene. Co-regulation is not a metaphor. A calm nervous system in the room is the most reliable tool anyone present has. In the week after. This is the part people skip. Sleep, food, daylight, gentle movement, and a small number of conversations with people who can hear you without flinching. Social connection belongs on the evidence list alongside breathing and exercise. Do not schedule anything you would dread on day three. Ongoing. If you have an inflammatory or autoimmune condition and you are interested in vagus nerve stimulation, that is a conversation with a physician about an FDA-cleared device and real trial data. It is not a conversation about an ear clip you saw on TikTok.

What to be skeptical of

Anything promising a reset. Anything claiming to fix inflammation through humming. Any device marketed with Tracey's research as its credential when the research involved surgical implantation and precise targeting. Any framework that tells you your nervous system is broken and can only be repaired by purchase. Your nervous system is not broken. It is doing what it learned to do, in conditions that made that learning reasonable. Changing it is slower and less purchasable than the internet suggests, and considerably more possible than despair suggests.

Working with this

At Brooklyn Balance, nervous system regulation is the spine of how I approach preparation, sitting, and integration. Not as a hack, and not as a belief system. As the practical question of whether your body currently believes it is safe, and what would need to be true for that to change. If you are preparing for a psychedelic experience, sitting with a difficult one, or trying to make sense of something that happened months ago and has not settled, that is the work I do.

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Josh Jupiter is a psychedelic integration coach and founder of Brooklyn Balance, a wellness practice in Brooklyn, New York. This article is for educational and informational purposes only and does not constitute medical or legal advice. For guidance on any of the therapeutic options discussed, please consult a qualified healthcare provider. For information on clinical trials, visit ClinicalTrials.gov.

Ready to go deeper? Reach out to Josh to learn about one-on-one integration coaching, group programs, and upcoming workshops at Brooklyn Balance.