The 40Hz Protocol: Ashtanga Yoga as a Multimodal Gamma Entrainment System

A 2024 review in Frontiers in Neuroscience catalogues the methods researchers use to induce gamma oscillations in the human brain: sensory stimulation, optogenetic modulation, photobiomodulation, and transcranial electrical or magnetic stimulation. The authors are interested in therapeutic applications—Alzheimer’s disease, cognitive decline, neurological rehabilitation. They are looking for ways to externally trigger the brain’s 40Hz rhythms, gamma oscillations that govern connectivity between distinct brain regions essential to perception, motor control, memory, and emotion.

Reading the paper, I kept having the same thought: Ashtanga yoga already does this. Not metaphorically. Not approximately. The classical Mysore method, practiced as a complete system, delivers functional analogs to every one of these stimulation categories—simultaneously, and endogenously.

That is worth sitting with for a moment.

Sensory Stimulation: The Counted Practice as Oscillatory Signal

Researchers induce gamma entrainment through sensory stimulation by exposing subjects to rhythmic auditory or visual input at 40Hz—flickering lights, clicking sounds, precisely metronomic patterns. The brain, encountering a rhythmic external signal, begins to synchronize its own oscillatory activity to that frequency. The clinical literature calls this the frequency-following response.

In the Mysore room, the primary sensory entrainment signal is breath—specifically ujjayi pranayama, the “victorious” breath that produces a soft oceanic sound through slight glottic constriction. Ujjayi is not simply a breathing technique. It is a self-generated oscillatory signal, rhythmically consistent, repeated hundreds of times across a ninety-minute practice. The practitioner creates the signal and receives it simultaneously, which means the entrainment feedback loop is tighter than anything achieved by an external speaker.

Layer in the counted vinyasa method—”ekam, dve, trīṇi,” each count anchoring an inhale or exhale to a specific movement—and you add a secondary rhythmic auditory-cognitive cadence. The nine drishti points, fixed gaze positions assigned to each posture, introduce a third channel: structured visual attention that modulates gamma in visual cortex specifically. This is not one sensory entrainment signal. It is three, running in parallel, all internally generated, all phase-locked to each other through the architecture of the vinyasa.

Photobiomodulation and Optogenetics: Light, Time, and the Practice Environment

Photobiomodulation uses near-infrared and red-spectrum light to affect neural tissue directly—modulating mitochondrial function, reducing neuroinflammation, influencing cortical oscillatory states. Optogenetic modulation, currently confined to laboratory settings, uses light-activated ion channels to control neuronal firing with extraordinary precision. Both methods share a common substrate: light as a signal that reorganizes neural behavior.

The traditional prescription that Ashtanga be practiced at sunrise is not sentimental. Morning light, particularly in the blue-spectrum wavelengths present at dawn, activates intrinsically photosensitive retinal ganglion cells that project directly to the suprachiasmatic nucleus—the master circadian clock. This entrains the practitioner’s circadian phase before movement begins. The cortical oscillatory state a practitioner brings to the mat at 6am is meaningfully different from the state at noon, and the traditional timing captures a specific neurobiological window.

Sun salutations—Surya Namaskara—orient the body repeatedly toward light. The thermal effects of sustained movement raise core temperature, which influences neural conduction velocity and oscillatory dynamics. These are not equivalent to clinical photobiomodulation devices. But they operate on the same biological substrate, through mechanisms the tradition intuited long before the vocabulary existed to name them.

Transcranial Stimulation: Bandha, Inversion, and the Endogenous Current

Transcranial electrical and magnetic stimulation—tDCS, tACS, TMS—work by applying external fields to the scalp that modulate the electrical environment of underlying cortical tissue. Weak currents shift neuronal resting membrane potentials; oscillating currents entrain cortical rhythms to applied frequencies. The clinical literature shows that gamma-frequency tACS can enhance working memory, perceptual binding, and cross-regional connectivity.

Mula bandha and uddiyana bandha—the root and abdominal locks central to Ashtanga practice—generate sustained intra-abdominal and intrathoracic pressure changes that propagate through the cerebrospinal fluid system. CSF pulsatility directly influences intracranial pressure dynamics and, through that mechanism, the electromagnetic environment of neural tissue. Inversions—headstand, shoulderstand, the many half-inversions distributed throughout the primary series—dramatically alter cerebral blood flow patterns and venous return dynamics.

None of this is identical to transcranial current stimulation. But the governing principle—that the physical manipulation of the body can alter the electrical and fluid dynamics of the brain—is the same. Bandha and inversion generate endogenous modulatory signals that affect the same tissue, through pathways the body already knows how to use.

The Complete System

Here is what I find remarkable: no single external stimulation device delivers all four categories simultaneously. A 40Hz light flicker device does one thing. A transcranial alternating current stimulator does another. Clinical photobiomodulation helmets do a third. Researchers studying gamma entrainment must design multimodal protocols, combining methods, to approach what happens in a single Ashtanga practice session.

Ashtanga, practiced as a complete system, delivers rhythmic sensory entrainment through breath, count, and gaze; circadian photoentrainment through timing and environment; physical modulation of CSF and cerebral blood flow through bandha and inversion; and proprioceptive rhythms through the fixed vinyasa sequence that feed back into gamma-band cortical processing. All of this runs concurrently. All of it is self-administered. None of it requires a device.

This is why the apparent rigidity of the traditional method—the fixed sequence, the prescribed breath ratios, the specific gaze discipline, the unwavering morning timing—begins to look different through this lens. What reads as ritual conservatism is, at the functional level, calibration. The system was tuned over centuries of observational refinement to produce a particular neurobiological effect. The traditional teachers did not have the vocabulary of gamma oscillations or CSF pulsatility. But they had something the researchers are still working toward: a complete protocol.

What This Changes

I want to be careful here about what I am and am not claiming. I am not saying that Ashtanga cures Alzheimer’s, or that practicing primary series is equivalent to wearing a clinical neurostimulation device, or that the tradition’s designers consciously understood gamma oscillations. The neuroscience literature I am drawing from is active and contested in places. The connections I am tracing are mechanistic hypotheses, not established clinical findings.

What I am saying is this: the precision of classical Ashtanga practice is not arbitrary, and the neuroscience of gamma entrainment gives us a new framework for understanding why specific elements of the method matter. The particular breath ratio, the specific drishti, the exact vinyasa count, the morning timing—each of these has been treated in popular yoga discourse as either sacred tradition (don’t question it) or outdated dogma (feel free to ignore it). Both framings miss the functional point.

When we understand the practice as a multimodal oscillatory entrainment system, we can begin to ask better questions. Which elements of the method are load-bearing for the neurological effect, and which are cultural scaffolding? What is the minimum viable protocol? How does the system respond to individual neurological variation—the student whose nervous system is already hyperactivated, or underregulated, or dysrhythmic from trauma? What does “modification” mean when the thing we are modifying is a calibrated frequency protocol?

These are not rhetorical questions. They are the questions I am actively working with in my teaching, in the Mysore program at The Yoga Club, and in the manuscript I am currently writing. Fifteen years of leading this practice has taught me that the system works—I have watched it work in federal employees, veterans, activists, beginners, and advanced practitioners. The neuroscience does not validate that experience so much as it begins to explain the mechanism. And mechanisms are useful, because they tell you what to protect.

A Note on Humility

The Frontiers in Neuroscience review I began with is primarily concerned with pathology—with gamma dysrhythmia in disease states, and how to restore function through external intervention. The researchers are looking for a way in.

The tradition I work in has been providing the way in for a long time. Not because it understood the neuroscience, but because it was built from sustained, careful attention to what human beings need in order to perceive clearly, move well, remember what matters, and feel something other than overwhelmed.

That is still the work. The gamma oscillations are just a more precise vocabulary for what the practice has always been trying to do.