The New Science Of Breath: James Nestor On Why Most People Are Breathing Wrong

Summary of The New Science Of Breath: James Nestor On Why Most People Are Breathing Wrong

by Rich Roll

2h 17m•February 2, 2026
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Overview of The New Science Of Breath: James Nestor On Why Most People Are Breathing Wrong

In this Rich Roll episode James Nestor (author of Breath) argues that most modern humans breathe inefficiently — largely mouth-breathing and shallow breathing — and that this single, overlooked behavior contributes to widespread problems: poor sleep, anxiety, asthma and other respiratory disease, hypertension, reduced athletic efficiency, and even developmental issues in children. Nestor traces the causes (structural jaw changes driven by softer industrial foods, sedentary posture, indoor air quality) and explains the physiology (why nasal breathing and balanced CO2 are important). He also offers practical diagnostics and step-by-step habits people can use to improve daytime and nighttime breathing.

Key takeaways

  • Most people default to inefficient mouth/chest breathing; nasal, diaphragmatic breathing is healthier and more efficient.
  • Nasal breathing produces nitric oxide, filters and conditions air, improves oxygen delivery and parasympathetic tone.
  • CO2 is essential for oxygen delivery (Bohr effect). Over‑breathing lowers CO2, causes vasoconstriction and reduces oxygen delivery to tissues.
  • Structural airway problems (narrow palates, deviated septum, inflamed adenoids/tonsils) are common today — linked to softer diets and lifestyle changes — and can force mouth breathing.
  • Poor breathing at night (mouth breathing/sleep-disordered breathing) causes major physiological harms rapidly; correcting nasal breathing often produces quick improvements.
  • Simple, low-cost tests and habits (self-assessments, snore apps, nasal strip, nasal taping protocols, breathing drills) can have measurable benefits. See “Action items” section.

Problems identified (what’s wrong and why)

Structural and developmental causes

  • Modern jaws are often narrower than ancestral skulls; malocclusion and crowded teeth are common.
  • Nestor links this change to industrial/soft diets: kids today chew far less than ancestors, which affects jaw and palate development during critical early years.
  • Narrow palates reduce nasal airway space, encouraging mouth-breathing.

Lifestyle contributors

  • Sedentary posture (slumped thorax) limits diaphragmatic movement and promotes shallow chest breathing.
  • Indoor, recycled air and poor ventilation increase CO2 and exposure to others’ exhalations — harming cognition, sleep quality and immune exposure.

Clinical/epidemiological links

  • Chronic mouth-breathing correlates with more cavities and altered oral microbiome.
  • Sleep-disordered breathing links to poor sleep, raised blood pressure, metabolic and cognitive consequences.
  • Emerging (and somewhat controversial) evidence suggests many children diagnosed with ADHD have underlying sleep-disordered breathing; treating airway obstruction (e.g., tonsil/adenoid removal, airway therapy) sometimes reduces ADHD-like symptoms.

Physiology and mechanisms (why nasal + diaphragmatic breathing matters)

  • Nasal breathing:

    • Filters, humidifies and warms air.
    • Produces nitric oxide in the sinuses — antimicrobial and vasodilatory; improves oxygen uptake.
    • Encourages slower, deeper breathing and diaphragmatic expansion.

  • CO2’s role:

    • CO2 facilitates oxygen release from hemoglobin (Bohr effect). Over-breathing removes too much CO2 → vasoconstriction and impaired oxygen delivery even when blood oxygen saturation looks normal.
    • Chronic over-breathing → alkalosis, sympathetic activation, anxiety-like states and systemic stress.

  • Shallow mouth/chest breathing:

    • Delivers less effective lung ventilation → more frequent breathing, increased perceived stress, reduced HRV, worse sleep, and long-term strain on physiology.

Evidence and notable studies / demonstrations from the episode

  • Archaeology/research tracing jaw narrowing and malocclusion to dietary changes following industrialization (Nestor cites long‑term anthropological research).
  • Stanford forced-breath study (Nestor participated): forced mouth-breathing for days produced rapid deterioration in sleep, spikes in snoring and sleep apnea-like results, increased blood pressure, reduced HRV and cognitive/fatigue symptoms — most effects reversed quickly when nasal breathing resumed.
  • Freediving and breath-hold training show humans can expand CO2 tolerance and control autonomic responses; these techniques illuminate limits and training effects for breath control.
  • Indoor CO2 measurements: Nestor’s team recorded high CO2 levels in many indoor spaces (classrooms, flights, hotels). High indoor CO2 correlates with cognitive impairment and elevated stress in studies.

(Note: some claims, especially about prevalence percentages and causal links to ADHD, remain contested and are the subject of ongoing research. Nestor presents a mix of published studies, clinical observations, and anecdotal reports.)

Practical, evidence-informed action items (what to do now)

Daily basics

  • Become an obligate nasal breather during rest: practice breathing in/out through the nose while seated, working, and walking (except when intense exertion forces mouth-breathing).
  • Diaphragmatic breathing drill: place one hand on upper chest and one on belly (near the navel). Breathe so the belly rises and the chest stays relatively still. Repeat several times a day.
  • Set phone alarms (4–10/day) as reminders to check breathing pattern and posture.

Night / sleep

  • Diagnose first: record your nighttime breathing/snoring with apps like SnoreLab or SnoreClock to see whether mouth-breathing or choking episodes occur.
  • Mouth-taping protocol (only for appropriate candidates): practice daytime nasal-only breathing first. Start with short periods wearing sleep tape during quiet daytime activities, gradually increase to nights. If you have nasal obstruction, chronic inflammation, or structural problems, do NOT tape — consult a clinician first.
  • Nasal strips: useful “training wheels” to increase nasal airflow (can reduce snoring for many people).
  • For suspected sleep apnea or severe snoring, get a formal sleep study or consult ENT/sleep specialist. CPAP helps many but has adherence issues; structural/airway fixes can be alternatives.

Testing and monitoring

  • CO2/air quality: consider a CO2 monitor (Nestor recommends accurate brands like Aranet) for classrooms, offices, flights, hotels. Aim to keep indoor CO2 as low as possible (ideally under ~1,000 ppm; below 500–800 ppm is better).
  • Quick CO2/CO2-tolerance check (as described in episode): there are simple household tests (BOLT/control‑pause and trainer variations). Use them as a baseline and to measure improvement over weeks — seek trained practitioners for formal testing.

When to seek professional help

  • Loud nightly choking, gasping, prolonged snoring, daytime sleepiness, or suspected apnea → see ENT/sleep clinic.
  • Children who snore, have mouth posture, bedwetting or behavioral/cognitive issues → consider airway-focused evaluation (ENT, orthodontist with airway specialization, or pediatric sleep clinic).
  • Never use mouth taping if you cannot breathe through the nose or have major nasal obstruction; consult a clinician first.

Cautions and safety

  • Don’t push breath-holding near water or during activities where fainting is dangerous.
  • Don’t abandon prescribed medications (e.g., asthma inhalers, sleep apnea CPAP) without medical oversight. Breathing practices can be complementary, sometimes helpful, but are not a guaranteed replacement for necessary medical treatment.
  • Breathwork modalities (Wim Hof, holotropic, etc.) can be powerful but may stress the system — use them appropriately and preferably under guidance.

Breathwork modalities — when they help and when they don’t

  • Buteyko-style training: focused on increasing CO2 tolerance by slowing and reducing breathing — helpful for asthma, anxiety and improving baseline breathing patterns.
  • Wim Hof / vigorous controlled hyperventilation + breath-hold: a hormetic (stress) practice that intentionally over-breathes then holds, training autonomic control and producing transient altered states; useful as an occasional practice but should not replace baseline nasal/diaphragmatic breathing training.
  • Holotropic/extended breathwork: intense, consciousness-altering sessions; can produce strong experiences but are not daily maintenance tools.
  • General rule: lock in normal nasal/diaphragmatic breathing first, then add specialized breathwork for specific goals.

Athletic and longevity implications

  • Lung function and capacity are highly predictive of healthspan/lifespan in longitudinal studies (e.g., Framingham-like findings): preserving lung capacity matters.
  • Athletes benefit from improved CO2 tolerance and diaphragmatic efficiency — training that increases “fuel tank” (lung capacity and tolerance) improves endurance and efficiency.
  • Trainers increasingly focus on breathing (CO2 tolerance, nasal breathing) before adding other layers of training for endurance athletes; habit change can extend athletic longevity.

Children, sleep-disordered breathing, and ADHD (controversial but important)

  • Nestor reports clinicians/dentists observing that many children diagnosed with ADHD have sleep-disordered breathing; in some documented cases, treating airway obstruction (tonsil/adenoid removal, orthodontic/airway interventions) reduces ADHD-like symptoms.
  • He stresses this is not a single-cause explanation for ADHD, but an underexplored contributing factor worthy of medical evaluation in symptomatic children (snoring, restless sleep, daytime sleepiness, behavioral issues).

Notable quotes from the interview

  • “You're getting the majority of your energy not through food and drink — it's through your breathing.”
  • “CO2 is the divorce lawyer.” (i.e., CO2 is what enables oxygen to separate from hemoglobin and reach tissues)
  • “Most of us are doing it in a dysfunctional way… this is one of the main reasons they're so sick and they're not getting better.”

Quick-start checklist (first 4 things to do this week)

  1. Record one night of your sleep with an app (SnoreLab/SnoreClock) to see if you mouth-breathe or snore.
  2. Practice diaphragmatic nasal breathing 5 minutes, twice a day (hand on belly → expand on inhale, contract on exhale).
  3. Set 4 phone alarms/day: on each, check if you are nasal breathing and using belly breathing.
  4. If you travel or work indoors a lot, buy/borrow a CO2 monitor and check your office, classroom or hotel room; open a window or ask for better ventilation if levels are high.

Resources & tests mentioned

  • Snore apps: SnoreLab, SnoreClock (for home recording)
  • CO2 monitors: consumer models like Aranet (Nestor recommends accuracy)
  • Tests: BOLT/control pause and trainer exhale/hold assessments (useful as baseline)
  • Professionals to consult: airway-focused dentists/orthodontists, ENT/sleep specialists, pediatric sleep/ENT for children

Final note: Many of Nestor’s claims combine established physiology (nasal nitric oxide, CO2 role) with clinical observations and some controversial epidemiologic links. Some areas (e.g., ADHD causality, prevalence figures) remain active research topics — the practical, low-risk steps (nasal diaphragmatic training, diagnosis of sleep problems, improving indoor ventilation) are accessible starting points and often produce measurable benefits.