Essentials: Breathing for Mental & Physical Health & Performance | Dr. Jack Feldman

Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent, science-backed tools for mental and physical performance. I’m Andrew Huberman. Today, we return to my conversation with Dr. Jack Feldman, my go-to on how the brain controls breathing. To kick us off, what actually generates a breath?

We breathe to bring in oxygen and clear carbon dioxide, which keeps blood pH in a tight range. The diaphragm and rib cage expand the chest, pressure drops like pulling open a balloon, air flows in, and a brainstem region called the pre-Botzinger complex sparks each inspiratory burst; exhale is mostly passive recoil.

Is there a meaningful difference between nose and mouth breathing for how the diaphragm and intercostals fire?

At rest we default to the nose; during higher demand we open the mouth to move more air. The diaphragm and intercostals do their job either way, so the muscle pattern is largely indifferent to the route.

Walk us through the key brain centers you and others have identified.

Beyond the pre-Botzinger complex, we found a second oscillator near the facial nucleus that drives active exhalation during exertion. Another critical site, the retrotrapezoid nucleus, acts as a central CO2 sensor to stabilize brain pH.

Evolution helps explain the layout: mammals gained the diaphragm, a remarkably efficient muscle that lets us expand a vast lung surface area with minimal effort. Hundreds of millions of alveoli create roughly a tennis-court’s worth of membrane; even a small downward pull of the diaphragm moves enough fresh air to raise blood oxygen effectively.

Do you think the diaphragm helped enable larger mammalian brains?

Yes. A diaphragm makes continuous, efficient oxygen delivery possible; without it, you’re closer to amphibian-style breathing and its limits.

There’s lots of advice to “breathe with your belly.” Are you convinced diaphragmatic breathing is uniquely healthier?

I’m agnostic about belly versus chest emphasis. The meaningful shifts in mood and cognition likely arise from how breathing patterns engage brain circuits, not from which specific respiratory muscles you highlight.

What are physiological sighs, and what are they good for?

We reflexively take a larger breath about every five minutes to pop open tiny alveoli that tend to collapse, preserving gas exchange. Ventilators mimic this with periodic bigger breaths because normal-sized breaths are not enough to reopen those units.

People can stop breathing with sedatives or drug combinations; could suppressed sighs or gasps be part of that risk?

As mammals near death, breathing slows, stops, and large gasps can appear; those may help re-arouse breathing. If drugs blunt that ability, a person may not self-resuscitate, which could tip the balance toward fatal asphyxiation.

How does changing breath influence brain state, and not just the other way around?

We developed a mouse protocol that slowed breathing roughly tenfold for thirty minutes a day over four weeks; those mice froze far less in a standard fear test, comparable to major amygdala manipulations. It’s powerful evidence because mice don’t show placebo effects, so the breathing change itself likely drove the shift.

Quick nod to public funding that supports research on meditation, breathwork, and related practices—it matters. And I love that this work helps define minimum effective doses so more people can get real benefits.

Breathing touches many circuits beyond the pre-Botzinger complex. Nasal airflow rhythms the olfactory bulb, lung stretch drives strong vagus nerve input to the brainstem, CO2 and pH tune ventilation and anxiety, and voluntary breathing sends descending motor commands with collateral effects across the brain.

Are other body functions coordinated with breath in meaningful ways?

Heart rate waxes and wanes with each breath, pupils oscillate too, and rhythmic breathing can disrupt maladaptive brain loops like those seen in depression. Think of it as a gentle, prolonged perturbation that weakens stuck circuits, akin in spirit—though far milder—to brain stimulation therapies.

Given all this, what do you personally practice?

I get a lot from five to twenty minutes of box breathing, often after lunch to lift energy. I’m also exploring very slow breathing to compare effects.

What’s your box-breathing pattern?

Inhale five seconds, hold five, exhale five, hold five; sometimes I double the counts to ten. It’s simple and reliably helpful.

You’ve also looked at magnesium for brain function. What interests you about magnesium threonate?

Disclosure: I advise a company in this space. A former trainee found that raising magnesium strengthened synaptic plasticity in neurons by lowering background activity, but most salts don’t enter the brain well; magnesium threonate appears to cross barriers more effectively, likely by engaging transporters.

In a double-blind study of people with age-inappropriate cognitive decline, placebo improved their general intelligence score by about two years, while magnesium threonate improved it by about eight. That moved cognition closer to biological age.

The commercial dose mirrors the trial; I take half because my blood magnesium rose to high-normal and that’s where I wanted to stay. Friends often report better sleep and sometimes sharper alertness.

The mechanistic story hangs together, and I appreciate your rigor. We covered a lot, and I’m already lobbying for part two; thank you for pioneering this field and for sharing both science and practice with us today.

Thanks for the chance to discuss it; I’d be glad to come back.

Wonderful. We’ll do it. Thanks again, Jack.