Neuroscience Reveals: The Real Reason Breathwork Changes Your Brain

Summary

Brian from 9D Breathwork argues that breathing’s effects on the brain are not simply about taking in more oxygen. He says carbon dioxide (CO₂) helps regulate brain blood flow and the release of oxygen from hemoglobin into tissues. In his account, breathing rapidly can lower CO₂, constrict blood vessels in the brain, and make oxygen harder for tissues to use—even while blood oxygen saturation remains high.

Main Ideas

• CO₂ is more than a waste gas. The video says chemoreceptors in the brainstem and arteries respond strongly to rising CO₂, helping trigger the urge to breathe.
• CO₂ affects cerebral blood flow. Higher CO₂ is described as widening brain blood vessels, while lower CO₂ can constrict them. The video says fast, deep breathing may reduce CO₂ and lower brain blood flow.
• The Bohr effect links CO₂ to oxygen delivery. As presented in the video, CO₂ helps hemoglobin release oxygen into tissues. When CO₂ falls, hemoglobin can hold onto oxygen more tightly.
• The video describes research on intensive breathwork. It cites a 2025 study involving 42 experienced practitioners, saying MRI measurements showed a substantial drop in brain blood flow during high-ventilation breathing, especially in the left posterior insular cortex. The speaker says the size of the decrease was associated with the intensity of participants’ altered-state experiences. He also notes that the study was small and had no control group, so its findings are preliminary rather than conclusive.
• Intentional, temporary changes are distinguished from chronic over-breathing. The speaker says that repeatedly over-breathing without noticing may be different from a guided session that deliberately changes breathing for a limited time and then returns to slower breathing.

Practices Described

BOLT-Style Breath-Hold Test

The video calls this the BOLT score (“body oxygen level test”) and presents it as a rough way to track the point at which the urge to breathe first appears:

1. Breathe normally through your nose for about two minutes.
2. Take one ordinary, unforced nasal breath, then exhale gently.
3. Hold your breath and start timing; pinch your nose if needed.
4. Stop at the first clear urge to inhale—not at the point of strain or desperation.
5. Let your breathing return to normal.

The video gives these approximate ranges:

• Under 10 seconds: low tolerance
• 10–20 seconds: common
• 20–30 seconds: “pretty good”
• Over 30 seconds: “great”

The speaker stresses that this is not a breath-holding contest. Do not do it in water or while driving. He advises people who are pregnant or have heart problems, high blood pressure, or a seizure history to skip it and consult a doctor first. Stop if dizzy.

Slow Nasal-Breathing Practice

• Practise for five minutes a day, breathing through the nose with the mouth closed.
• Inhale gently for four seconds and exhale for six seconds—about six breaths per minute.
• The speaker suggests doing this most days for 30 days and checking the breath-hold score about once a month, rather than testing daily.
• He also describes noticing the jaw, throat, ribs, and pulse as breathing becomes easier and slower.

The video frames a higher tolerance score as a possible sign of less sensitivity to CO₂ and less habitual over-breathing, while emphasizing that the score itself is not the goal.

Caveats and Closing Message

The speaker acknowledges that the cited research is limited and says the video is not medical advice or a substitute for professional care. He also cautions against the idea that breathing harder necessarily gives the brain more usable oxygen. His practical recommendation is to record a baseline test, try the five-minute slow-breathing practice, and reassess after 30 days.

Speakers and Sources Featured

• Brian, presenter from 9D Breathwork.
• A 2025 study attributed in the subtitles to researchers at Brighton and Sussex Medical School and published in PLOS ONE. The speaker says it examined 42 experienced high-ventilation breathwork practitioners using MRI.
• A second 2025 paper attributed in the subtitles to “Havenit and colleagues”; the subtitle spelling may be inaccurate.
• Physiology concepts and sources discussed: chemoreceptors, cerebral blood-vessel dilation and constriction, and the Bohr effect.