The Science of High-Ventilation Breathwork: What Research Tells Us

For decades, high-ventilation breathwork practices like Rebirthing and Holotropic Breathwork lived mostly on the fringes of psychology — practiced widely, but studied rarely. In the last few years, that has quietly changed. A growing body of peer-reviewed research is beginning to describe what happens in the body and brain when we breathe faster and deeper than usual for extended periods.

The early findings are interesting, and some of them echo what practitioners have reported for half a century — but many questions remain open.

What Counts as High-Ventilation Breathwork?

High-ventilation breathwork refers to practices that intentionally increase the rate and depth of breathing well beyond resting levels for a sustained period — typically 30 to 90 minutes. This includes Rebirthing, Holotropic Breathwork, Conscious Connected Breathing, and many modern transformational breathwork styles.

Most of these styles lead to over-breathing, which lowers CO₂ and can cause respiratory alkalosis; how strongly depends on the style and the person: carbon dioxide (CO₂) levels drop, blood pH rises, and cerebral blood flow temporarily decreases. Many people experience this as an altered state of consciousness.

What the Latest Science Shows?

Measurable reductions in stress and anxiety:

A key synthesis of breathwork trials comes from a 2023 meta-analysis published in Scientific Reports (Fincham et al.), which pooled data from 12 randomized controlled trials (RCTs). The authors concluded that breathwork interventions produce small-to-medium, statistically significant improvements in stress, anxiety, and depressive symptoms compared to non-breathing control conditions, while noting that many of the trials had a high risk of bias.

Fast and slow breathing are thought to work through different mechanisms. A 2023 study in Cell Reports Medicine (Balban et al., Stanford University / Huberman Lab) compared several daily five-minute practices over one month. The breathing practices improved positive mood more than mindfulness meditation, and cyclic sighing (a slow-breathing protocol emphasising prolonged exhalations) showed the largest daily improvement in positive mood and the greatest reduction in resting respiratory rate. The study was small and run remotely, so these results still need confirming. Together, these studies suggest that different breathing styles may affect the nervous system in different ways.

An altered state that can be measured:

Small studies, including work by researchers connected to the Imperial College Centre for Psychedelic Research, suggest that a single session of high-ventilation breathwork can induce a non-ordinary state of consciousness. On standard questionnaires (such as the MEQ30 and 11-D ASC scales), some participants report intensities that overlap with those reported after psychedelics. These comparisons come from separate, small studies rather than direct head-to-head trials.

Participants often report experiences such as

• Ego dissolution and a reduced sense of time/space
• Strong emotional release
• Vivid visual imagery
• A sense of interconnectedness

A few small EEG and brain-imaging studies during high-ventilation breathing report changes in brainwave activity and in how brain networks, such as the Default Mode Network (DMN), connect. Some researchers compare these patterns with psychedelic states and deep meditation, but the findings are early and not yet consistent across studies.

What Actually Happens Physiologically?

The basic chemistry of sustained overbreathing is well understood; how it shapes the inner experience is much less clear.

• Hypocapnia and Respiratory Alkalosis: Rapidly expelling CO₂ causes blood CO₂ levels to drop (hypocapnia). This raises blood pH, making it more alkaline.
• Temporary Shift in Cerebral Blood Flow: Low CO₂ narrows the brain's blood vessels, temporarily reducing blood flow to the brain; the further CO₂ falls, the larger the drop. Some small imaging studies report reductions in regions involved in executive control and self-monitoring.
• Autonomic Spikes & Parasympathetic Rebound: The intense phase creates a spike in sympathetic activation (fight-or-flight), often followed by a calmer, parasympathetic phase (rest-and-digest) during integration. Whether this leads to lasting changes in heart-rate variability (HRV) has not been well studied.
• Neurochemical Release: Studies of a related technique, the Wim Hof Method, measured a clear rise in adrenaline during the breathing exercises. Some researchers propose that the body's own opioid and endocannabinoid systems play a role in the euphoria, heightened sensory awareness and altered pain perception some people report, but this has not been shown directly.

Why do your hands tingle? Low blood CO₂ reduces the amount of free (ionised) calcium in the blood and makes nerves more excitable. This explains the temporary tingling (paraesthesia) and, at stronger levels, the muscle cramping (tetany) well known to experienced breathworkers.

Emotional Processing:

Research on Holotropic Breathwork is small and mostly uncontrolled. A long-running study of workshop participants reported increases in measures of self-awareness (Miller & Nielsen, 2015), but it had no control group, and reviews describe the method as a possible adjunct to psychotherapy that still needs proper trials (Rhinewine & Williams, 2007).

One hypothesis is that the altered state loosens top-down mental control, so that emotions and body sensations surface more easily. Ideas from polyvagal theory or memory reconsolidation are sometimes used to explain this, but they have not been tested in breathwork, and polyvagal theory itself is debated. In a safe, supportive environment, many people experience this as a chance to feel and express emotions without judging them. For trauma and PTSD specifically, see breathwork and emotional release.

What the Evidence Says About Safety?

Studies so far suggest that high-ventilation breathwork is usually well tolerated by screened, healthy adults, although side effects are not always reported systematically. Because it strongly affects body chemistry, it is not risk-free.

Documented transient effects include dizziness, involuntary muscle contractions (tetany), and intense emotional processing. For this reason, research studies typically exclude people with conditions such as the following.

• Cardiovascular disease or severe hypertension
• Epilepsy or history of seizures
• Pregnancy
• Glaucoma or retinal detachment
• Bipolar disorder, schizophrenia, or acute psychosis

If you are not sure if breathwork is safe for you to practice, please try our safety check before attending a session.

What the Science Does Not Yet Tell Us?

To remain clear and objective, we must acknowledge the current boundaries of breathwork research.

• Sample sizes remain modest: Many studies feature fewer than 100 participants.
• Long-term data is sparse: Longitudinal follow-up beyond 3 to 6 months is still rare.
• Mechanistic overlap: It is not yet fully clear how much of the reported benefit comes from the breathing itself, and how much from setting, expectations and support.

The Bottom Line:

Research is beginning to test what breathwork practitioners have observed for half a century: breathing faster and deeper within a structured, safe container can noticeably shift the nervous system, and many participants describe emotions surfacing and feeling calmer, clearer and more connected afterwards.

It is not a magical cure-all, nor a total substitute for medical care or psychotherapy. Rather, it is a promising practice with real, measurable effects on body chemistry, whose benefits for mental health are still being studied.