Anuloma Viloma TimerA 2025 PLOS ONE study from the University of Sussex and Brighton and Sussex Medical School quietly produced the first peer-reviewed brain scans of breathwork in action. They got participants into a functional MRI, ran a structured breathing protocol, and watched the blood flow in real time. The pattern was new to medicine, and nine months on it still has not surfaced in consumer wellness coverage. That is unusual for a finding this clean and this visual, so it is worth walking through carefully.
What the Sussex group actually did
The Colasanti Lab at BSMS recruited experienced breathwork practitioners and ran them through a structured high-ventilation breathwork session inside the scanner. The neuroimaging endpoint was regional cerebral blood flow, measured with arterial spin labelling, a technique that produces quantitative perfusion maps without the timing artefacts that arise from blood-oxygen-level-dependent imaging during respiratory tasks.
That methodological choice matters. Most prior fMRI breathing research has been confounded by the fact that breath rate itself shifts the blood oxygenation signal the scanner is trying to measure, which is why we did not have clean brain scans of breathwork before this group did the work. Arterial spin labelling sidesteps the confound. The result is a perfusion map you can actually read.
What the scans showed
Two patterns separated breathwork from the resting baseline.
Blood flow decreased in the regions that track body state. The insula, the precuneus, the parts of the parietal cortex that sit at the centre of the brain’s interoceptive map. These are the regions that build the felt sense of “here is the inside of my body, this is what it is doing right now.” During the breathwork session, perfusion to that map dropped.
Blood flow increased in the regions that store and consolidate emotion-laden memory. The amygdala. The hippocampus. The medial temporal cortex. These regions normally activate when the brain is processing emotionally salient material, particularly material with a memory component.
The dose-response correlation was the part the reviewers cared about. The bigger the perfusion shift, the bigger the subjective shift the participant reported. The brain change tracked the experience the participant was having.
What that pattern means, in plain terms
The wellness shorthand for breathwork has long been “it calms the nervous system.” That shorthand is not wrong, but the Sussex pattern is more specific than that, and the specificity matters.
The drop in interoceptive signal is consistent with the felt experience that the body-as-object recedes. The body becomes less of the foreground story. The rise in amygdala-hippocampus activity is consistent with material from emotional memory becoming more available, sometimes vividly. People who have done extended breathwork sessions know this experience well. The Sussex paper is the first time the experience has been mapped onto a peer-reviewed perfusion image.
This is also where the careful distinction has to land. The Sussex protocol was high-ventilation breathwork, not slow nasal pranayama. The doses are different. The phenomenology is different. The applications are different. A study showing dramatic perfusion shifts during a high-ventilation session does not automatically transfer to a five-minute round of nadi shodhana on a Tuesday morning.
Same family, gentler dose
Slow nasal alternate nostril breathing sits in the same broader family as the Sussex protocol but at a much lower dose along several axes. The breath rate is slower. The carbon dioxide swing is smaller. The duration is shorter. The intent is regulation rather than experience-induction.
The mechanism that does carry across is the one Communications Psychology covered in a companion 2025 paper on carbon dioxide modulation. Breathwork techniques modulate CO2, and CO2 is one of the most direct chemical levers the brain uses to set vascular tone, neuronal excitability, and emotional reactivity. Slow nasal breathing nudges CO2 in the calming direction. High-ventilation breathwork swings CO2 in the opposite direction, much harder. Two different points on the same dial.
For the question “what does daily nadi shodhana actually do to a brain,” the Sussex study is not a direct answer. It is a proof that the dial exists, that breath-driven changes in regional blood flow are real and measurable, and that the brain regions involved are exactly the ones a slow practice would want to reach in a gentler way: the body-state map and the emotional-memory hub.
Why this story has not surfaced yet
Three reasons, probably. First, PLOS ONE neuroimaging papers are technical and the abstract does not contain the words “psychedelic” or “anxiety,” which is what most consumer wellness pickup needs to bite. Second, the high-ventilation protocol the Sussex team used has been associated in the press with a specific commercial breathwork brand, and reviewers are reasonably cautious about coverage that reads as a free advertisement. Third, the dose-response framing requires a paragraph of explanation before it lands, and most wellness desks have a one-paragraph budget.
That is fine. The paper is open access. The findings are clean. Sharing the link is enough.
Where Anuloma Viloma fits
Anuloma Viloma is a structurally accurate timer for slow nasal alternate nostril breathing. It enforces the equal-length inhale, exhale, and pause cycles that the practice asks for. It alternates nostrils correctly on every cycle. It is free, with no subscription necessary for the core practice.
The Sussex study is not a study of nadi shodhana. It is a study of a louder cousin. The reason it is worth sitting with this week is that it produces the first published brain-perfusion image of breathwork as an active intervention, and it lays out the regions of the brain that any breath-driven practice is reaching toward. A daily five-minute round of nadi shodhana sits at the gentle end of that family. The mechanism is the same. The dose is different.
If your clinician, your therapist, or your training partner has not seen the Sussex paper yet, the link is below. It is the kind of paper that takes ten minutes to read and changes how a thoughtful practitioner talks about breathwork for the next year.
Anuloma Viloma Timer is free on the App Store. No subscription necessary.
References
- Colasanti A, et al. Cerebral blood flow changes during a high-ventilation breathwork practice: a quantitative arterial spin labelling fMRI study. PLOS ONE, 2025. https://journals.plos.org/plosone/
- CO2 modulation and breathwork. Communications Psychology, 2025.
- Mutze C, Mitzinger D, Haller H. Effectiveness of pranayama for mental disorders: a systematic review and meta-analysis of randomized controlled trials. Frontiers in Psychiatry, 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC12392162/
- Nadi Shuddhi Pranayama and HRV in Young Adults. PMC12331837. https://pmc.ncbi.nlm.nih.gov/articles/PMC12331837/