The Neuroscience of Breathwork and Altered States: From Holotropic Breathing to the Wim Hof Method

The Simplest Drug Is No Drug at All

Every psychedelic substance, every shamanic plant medicine, every neurotransmitter that modulates consciousness — all of them are attempts to shift the brain’s chemistry. But the most accessible, most ancient, and arguably most powerful tool for altering consciousness requires no substance at all. It is the breath.

By deliberately changing how you breathe — faster, slower, deeper, shallower, through one nostril, held at the top, held at the bottom — you directly manipulate the chemistry of your blood, the electrical activity of your brain, and the operating state of your nervous system. You can induce states ranging from deep calm to ecstatic trance, from analytical clarity to visionary experience, from the profound relaxation of parasympathetic dominance to the altered perceptions of transient cerebral hypoxia.

The shamans of every tradition knew this. Stanislav Grof confirmed it clinically. Modern neuroscience is now mapping exactly how and why it works.

Stanislav Grof and Holotropic Breathwork

Stanislav Grof, a Czech-born psychiatrist, spent the first two decades of his career (1950s-1970s) as one of the world’s leading researchers on LSD-assisted psychotherapy. Working first in Prague and then at the Maryland Psychiatric Research Center, Grof guided over 4,000 LSD sessions and developed a comprehensive cartography of the psyche based on the non-ordinary states of consciousness these sessions revealed.

When LSD was prohibited in the late 1960s and 1970s, Grof faced a practical problem: he had mapped vast territories of the human psyche accessible through psychedelics, but the key to those territories had been taken away. His solution, developed together with his wife Christina Grof, was Holotropic Breathwork — a method that uses accelerated breathing, evocative music, and focused bodywork to produce states of consciousness nearly identical to those produced by psychedelics.

The discovery was not accidental. Grof had observed that many cultures use breath manipulation to alter consciousness — from yogic pranayama to the hyperventilation techniques of certain shamanic traditions to the breathing patterns associated with emotional catharsis. He synthesized these observations into a structured therapeutic methodology.

The Holotropic Breathwork Protocol

A typical holotropic breathwork session involves:

Accelerated breathing. Participants breathe faster and deeper than normal — not violently, but with sustained intensity — for 1-3 hours. There is no specific prescribed rhythm; participants are encouraged to find their own breathing pattern and allow it to evolve.

Evocative music. The session is accompanied by carefully curated music that follows an arc from rhythmic and driving to emotionally expansive to meditative and integrating. The music serves the same function as the shaman’s drum — providing rhythmic entrainment and emotional guidance.

Bodywork. Trained facilitators provide focused bodywork to address areas of physical tension or energy blockage that emerge during the session.

Mandala drawing. After the session, participants create visual representations of their experience, beginning the integration process.

What Grof Discovered

Grof found that holotropic breathwork could reliably produce the full range of non-ordinary states he had previously observed only with psychedelics:

• Reliving of biographical memories, including birth experiences
• Perinatal experiences (related to the birth process)
• Transpersonal experiences (past lives, archetypal encounters, cosmic consciousness)
• Emotional catharsis and physical release
• Mystical and spiritual experiences
• Encounters with death and rebirth

Grof described these findings as confirmation that hyperventilation, combined with evocative music and bodywork, produced nearly identical results to his earlier LSD research. The states of consciousness were not drug effects — they were capacities of the human nervous system, accessible through multiple doorways.

The Neuroscience of Hyperventilation-Induced Altered States

Modern research has begun to clarify exactly what happens in the brain during sustained hyperventilation. The mechanisms are complex, multilayered, and remarkably precise in their effects:

Blood Chemistry Shifts

Respiratory Alkalosis. Rapid breathing expels CO2 from the blood faster than metabolism produces it. This drops blood CO2 levels (hypocapnia) and raises blood pH — a condition called respiratory alkalosis. Normal blood pH is approximately 7.4; during sustained hyperventilation, it can rise to 7.5-7.6 or higher.

Decreased Cerebral Blood Flow. CO2 is a potent vasodilator in the brain. When CO2 drops, cerebral blood vessels constrict, reducing cerebral blood flow (CBF) by 30-40%. This is not brain damage — it is a reversible, physiological response. But it produces transient cerebral hypoxia — reduced oxygen delivery to the brain.

Neuronal Hyperexcitability. Alkalosis changes the behavior of ion channels in neural membranes, making neurons more excitable. Falling CO2 levels result in elevated sensory and motor nerve potentials and bursts of spontaneous discharges. The brain becomes, temporarily, more electrically active and less predictably organized.

The Bohr Effect. Alkalosis increases hemoglobin’s affinity for oxygen — meaning oxygen binds more tightly to hemoglobin and is released less readily to tissues. This paradox — more oxygen in the blood but less delivered to the brain — contributes to the altered state.

Brain Imaging Findings

A 2024 study published in PLoS ONE investigated the neurobiological substrates of altered states induced by high-ventilation breathwork accompanied by music. Using neuroimaging, the researchers found:

Reduced activity in posterior insula and parietal operculum. The reduction of regional cerebral blood flow in a cluster localized within the left posterior insula and left parietal operculum predicted the intensity of altered states. These regions are involved in interoception — the brain’s monitoring of internal bodily states. When these regions become less active, the brain’s model of “the body as it normally is” begins to dissolve.

Mismatching interoceptive predictions. The researchers proposed that the key mechanism may be mismatching interoceptive predictions — when the brain’s expectations about internal bodily sensations do not align with the actual sensations produced by hyperventilation. This mismatch forces the brain to update its model of bodily reality, producing the subjective experience of altered consciousness.

A 2025 study published in Communications Psychology, titled “Decreased CO2 saturation during circular breathwork supports emergence of altered states of consciousness,” confirmed that decreased end-tidal CO2 (EtCO2) is a critical factor in catalyzing altered states during breathwork and may predict both subacute psychological and physiological outcomes.

The Comprehensive Review

A major 2023 review titled “High ventilation breathwork practices: An overview of their effects, mechanisms, and considerations for clinical applications” synthesized the available research and identified the following key mechanisms:

1. Respiratory alkalosis causing cerebral vasoconstriction and transient hypoxia
2. Neuronal hyperexcitability from altered ion channel function
3. Sympathetic nervous system activation followed by parasympathetic rebound
4. Disruption of default mode network function through altered cerebral blood flow patterns
5. Interoceptive prediction errors driving metacognitive shifts
6. Vagal stimulation through sustained deep breathing patterns

The Wim Hof Method: Breathing, Cold, and Conscious Control

Wim Hof, the Dutch “Iceman,” developed a method combining specific breathing techniques with cold exposure and meditation that has been the subject of multiple scientific studies. While culturally distinct from shamanic practice, the Wim Hof Method (WHM) exploits the same neurophysiological mechanisms.

The Breathing Protocol

The WHM breathing protocol consists of:

1. 30-40 cycles of deep, rapid breaths (controlled hyperventilation)
2. Breath retention at low lung volume (holding the breath after exhalation) for as long as comfortable
3. Recovery breath: deep inhalation held for 15-20 seconds
4. Repeat for 3-4 rounds

This protocol produces cyclical alternation between hyperventilation (respiratory alkalosis) and breath retention (hypoxia and hypercapnia), creating a dynamic oscillation in blood chemistry that has profound physiological and neurological effects.

Scientific Findings

Voluntary sympathetic activation. A landmark 2014 study published in the Proceedings of the National Academy of Sciences showed that WHM practitioners could voluntarily activate the sympathetic nervous system — previously thought to be entirely involuntary. Trained participants showed increased catecholamine (adrenaline) and cortisol release, and a remarkably mild innate immune response when injected with bacterial endotoxin compared to untrained controls. This was the first scientific demonstration that the autonomic nervous system and innate immune response can be voluntarily influenced.

Brain mechanisms of cold resistance. A 2018 Wayne State University study using fMRI and PET imaging revealed that Wim Hof’s breathing practice activated the periaqueductal gray (PAG) — a brainstem region involved in pain modulation and autonomic regulation — and generated significant heat through intercostal muscle activation. Practice of the method made skin temperature relatively invariant to cold exposure through increased sympathetic innervation and glucose consumption.

Metabolic waste clearance. A 2023 study proposed that WHM breathing may induce conscious metabolic waste clearance of the brain — essentially a waking activation of the glymphatic system, the brain’s waste removal pathway that normally operates primarily during deep sleep. If confirmed, this would represent a mechanism for breathwork to literally clean the brain.

Immune modulation. Multiple studies have confirmed that WHM practice modulates the immune system, with the combination of breathing exercises and cold exposure being most effective in decreasing inflammatory responses.

Breathwork and Near-Death Experience Parallels

The phenomenology of intense breathwork bears striking resemblance to near-death experiences:

• Tunnel vision and light experiences — cerebral vasoconstriction reduces peripheral visual processing, creating tunnel-like visual effects, while neuronal hyperexcitability can produce phosphene-like light experiences
• Out-of-body sensations — disrupted interoception and proprioception from altered brain perfusion patterns
• Life review and autobiographical memories — temporal lobe activation from neuronal hyperexcitability
• Encounter with deceased relatives or spiritual beings — temporal lobe and limbic system activation
• Feelings of peace, love, and transcendence — endorphin release and parasympathetic rebound
• Sense of crossing a threshold — the subjective correlate of progressive cerebral blood flow reduction

Grof himself noted these parallels, observing that holotropic breathwork could reproduce the full phenomenology of near-death experiences without any actual physiological threat to life. This led him to propose that NDEs may be partially explained by spontaneous hyperventilation — the rapid, shallow breathing (Cheyne-Stokes respiration) that often occurs during the dying process could trigger the same neurochemical cascade that holotropic breathwork deliberately induces.

Indigenous Breathwork Traditions

Long before Grof or Hof, indigenous cultures worldwide developed sophisticated breathwork technologies:

Yogic Pranayama. The oldest documented breathwork system, pranayama includes techniques ranging from the calming (nadi shodhana — alternate nostril breathing, which balances hemispheric activity) to the activating (bhastrika — “bellows breath,” a form of controlled hyperventilation) to the consciousness-altering (kumbhaka — extended breath retention). The yoga tradition classified these techniques by their effects on consciousness with a precision that modern neuroscience is only beginning to match.

Tummo Breathing. Tibetan Buddhist “inner fire” meditation involves specific breathing patterns combined with visualization to generate heat and alter consciousness. This is essentially the ancestral practice behind the Wim Hof Method, with centuries of additional contemplative development.

Shamanic Breathing. Many shamanic traditions use specific breathing patterns in conjunction with drumming, singing, and plant medicines. The combination of rhythmic breathing with theta-frequency drumming creates a dual-pathway entrainment — affecting the brain both through blood chemistry changes (breathwork) and auditory driving (drumming) simultaneously.

Sweat Lodge Ceremonies. The combination of heat, steam, darkness, and rhythmic chanting in traditional sweat lodge ceremonies creates conditions that promote hyperventilation, dehydration, and altered blood chemistry — a multi-modal approach to consciousness alteration that engages breathwork mechanisms alongside heat stress and sensory deprivation.

The Breath as Bridge

What makes breathwork unique among consciousness-altering technologies is its position at the intersection of voluntary and involuntary nervous system function. Breathing is the only vital function that is both autonomic (it happens automatically) and voluntary (you can consciously change it at will). This makes the breath a bridge — perhaps the only bridge — between conscious intention and the autonomic nervous system.

When you deliberately alter your breathing, you are reaching through the only available control surface into the autonomic machinery that governs your heart rate, your blood chemistry, your immune function, your emotional state, and your mode of consciousness. You are using the one voluntary key that opens the involuntary locks.

The shamans understood this. Every initiate in every tradition was taught to breathe — specifically, deliberately, with the understanding that the breath is not merely air moving through lungs but consciousness moving through the body. Modern neuroscience, with its measurements of blood CO2, cerebral blood flow, vagal tone, and brain entropy, is providing the mechanistic explanation for what the breath masters have always practiced.

The breath is the simplest technology. It is also the most profound. You carry it with you everywhere. It costs nothing. It requires no external substance, no equipment, no permission. And it can take you as deep as any molecule — because the molecule and the breath are working the same levers, opening the same doors, in the same brain.

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This article synthesizes research on holotropic breathwork by Stanislav Grof, scientific studies on the Wim Hof Method, the 2024 PLoS ONE neuroimaging study on breathwork-induced altered states, the 2025 Communications Psychology study on CO2 and consciousness, and the 2023 comprehensive review of high-ventilation breathwork practices.