Anuloma Viloma TimerA new paper in the journal Psychophysiology this month did something the breathwork literature has been circling for a decade. The researchers put 147 people inside an fMRI scanner and asked them to do two things, on two different days: breathe at their natural pace, and then breathe slowly at six per minute (a pace clinical biofeedback calls resonance frequency breathing). The scanner watched their brains the whole time.
Fifteen pairs of brain regions showed significantly increased functional connectivity during the slow breathing. Of those fifteen pairs, ten involved a subdivision of the insular cortex.
That detail matters. The insular cortex is the brain area where signals from the body (heart rate, gut, breath, blood pressure) get integrated with signals from cortical regions handling thought and emotion. It is the bridge between what your body is doing and what your mind is feeling. When the insula talks more to other regions, the brain is doing the work of joining inside-the-body to inside-the-mind.
For most of the last two thousand years, that integration was the explicit point of pranayama.
What the researchers measured
The Bates et al. paper enrolled 147 participants who fell into one of three groups: people with depression, people with substance use disorder, and people with no diagnosis at all. Each person did the same thing in the scanner: breathe naturally, breathe at six per minute, repeat. The slow pace was chosen because it lands at 0.1 Hz, the frequency at which heart rate variability (HRV) is at its highest. Researchers call this the resonance frequency, because the cardiovascular system seems to resonate with it. Slow nasal breathing at 0.1 Hz is also what cardiologists target when they use paced-breathing devices to train HRV.
The brain showed what the cardiovascular literature had already predicted at a physiological level: when the body slows the breath to that specific pace, the brain regions responsible for tracking internal state and translating it into experience start to coordinate more.
The insular cortex is the dominant story. Ten of fifteen significantly-changed connections involved an insular subdivision. The authors interpret this as the insula stepping up its role as an integrator: pulling in interoceptive signals from below (pulse, breath, gut), combining them with cognitive and emotional information from above (the prefrontal cortex and the anterior cingulate), and shaping the moment-to-moment sense of what is happening inside.
This was a fMRI study. It did not test anuloma viloma specifically. It did not test pranayama as a category. It tested the underlying pacing pattern that all of those techniques share at their physiological core.
Why this lines up with anuloma viloma
The most basic pacing instruction in anuloma viloma is the four-phase ratio at six breaths per minute: inhale, hold, exhale, hold, alternating nostrils. The exact ratio varies by school (1:1:1:1 for beginners, 1:4:2:2 for advanced practitioners, the Patanjali sutras suggest others), but six per minute is the pace that pranayama tradition has been pointing at since the practice was first transmitted in the Hatha Yoga Pradipika and the Gheranda Samhita. Two and a half thousand years before HRV biofeedback existed as a clinical method.
The Bates paper measured what happens in the brain when a person breathes at six per minute. The insular cortex pulled together body signals and emotional integration. The classical pranayama description of the same phase, written long before brain imaging, talks about the integration of prana (the breath) and chitta (the mind) at the moment of the held pause between breaths. The vocabulary is different. The physiological territory is the same.
The point of writing about this paper is not to claim that an fMRI study validates pranayama (that is reverse-engineering history). It is the other way around: a body of practice that has been transmitted, taught, and refined for centuries is now visible at the brain-imaging level. The mechanism it has been working on the whole time is becoming legible.
Why the insular cortex is the right brain region
Anxiety, depression, and the broader category of nervous-system dysregulation share one common feature: a poor fit between what the body is doing and what the mind makes of it. The body is racing; the mind reads it as danger and amplifies it. The body is calm; the mind reads it as nothing and dismisses it. Either way, the integration is off.
The insular cortex is the integration. Researchers who study interoception (the body’s sense of itself) have spent the last fifteen years showing that better insular function correlates with better emotional regulation, better recovery from stress, better outcomes in mood disorders. The Bates paper places slow nasal breathing at 0.1 Hz inside that conversation as a direct intervention.
A second paper, also published this year, comes at the same territory from the HRV side. Researchers at King’s College London ran a randomised study of resonance frequency breathing with 135 participants who scored 10 or higher on the GAD-7 (a measure of generalised anxiety). The breathing group showed improvements in both HRV and inhibitory control compared to the control group, in a single brief session. The Bates paper now adds the brain-imaging anchor that makes the HRV finding mechanistic.
What this means if you have never tried it
The instruction is unchanged from the way it was first transmitted. Close the right nostril with the thumb. Inhale through the left for a count of four. Close the left with the ring finger. Hold for a count of four. Open the right and exhale for a count of four. Inhale through the right for four. Close, hold, open the left, exhale. That is one round. Six rounds is roughly one minute at the six-per-minute pace. Fifteen rounds is roughly two and a half minutes.
Most clinical studies use fifteen-minute sessions. That is what Bates measured. That is what the King’s College team measured. It is also, not by accident, what every traditional Sanskrit instruction set recommends for a daily practice.
If you want to time the practice without counting in your head, Anuloma Viloma Timer is free on the App Store. No subscription necessary. It paces the four phases for you and, if you have an Apple Watch, shows the heart rate response in real time.
Bates, M. et al. Functional Connectivity Within the Central Autonomic Network Increases During Resonance Paced Breathing at 0.1 Hz. Psychophysiology, 2026. PMC12929929. King’s College London resonance frequency study: PMC12081530.