40 Hz Gamma Waves Explained: What They Do for Your Brain

The brain is essentially an electrical system that operates within rhythms. The firing neurons create rhythmic oscillations at different frequencies, corresponding to various states of mind. Amongst all these different frequencies, 40 Hz gamma waves have garnered more scientific attention during the last ten years in cognitive science..

The gamma waves at 40 cycles per second indicate that the brain is functioning at its maximum capacity, where it integrates data, maintains working memory, and forms thoughts from fragmented information. The study of Alzheimer's disease, aging, and cognition always leads scientists back to this frequency, because either interfering with or reinstating it seems to affect brain function.

This article explains what 40 Hz gamma waves are, what happens when they weaken, and what early research shows about stimulating them through light-based therapies.

The Science of Gamma Oscillations

Gamma waves fall in the 30 to 100 Hz range, with most research clustered around the 40 Hz mark. They show up on EEG recordings as rapid, synchronized electrical activity across large networks of neurons — the kind of coordinated firing that happens during demanding cognitive work.

Gamma waves do not become special because of speed alone. What makes them different from other types of waves is the level of coordination they represent. If gamma waves increase, they indicate that far-off brain areas are communicating with each other simultaneously – the cortex, hippocampus, and frontal lobes work together. It seems that such coordination is required to pay attention, learn, and understand complicated data.

A useful way to picture it: gamma waves act like a conductor's beat, keeping different sections of the neural orchestra in time during a difficult passage. When the beat falters, the sections drift apart.

How Gamma Waves Drive Cognitive Activation

Neuroscientists have long proposed that gamma activity underpins the brain's "binding" function — the process of stitching together information from different sensory and cognitive regions into a single coherent experience. Perceiving an object, following a conversation, working through a problem: all of these require that kind of integration, and gamma oscillations appear to be doing the stitching.

A 2025 study published in Nature Communications Biology confirmed that 40 Hz visual stimulation doesn't just activate early visual areas — it propagates through to the hippocampus and into the temporal and frontal lobes. That reach matters. Memory consolidation and executive function both depend on those regions talking to each other efficiently.

The hippocampus is worth singling out. It handles the formation and storage of new memories, and gamma synchrony within it tracks closely with working memory performance. Research on healthy adults has also found that 40 Hz auditory stimulation correlates with better scores on planning and problem-solving tasks. Gamma activity, in other words, isn't just a passive indicator of cognition — it seems to be driving it.

What Happens When Gamma Activity Declines?

Gamma oscillation reduction effects have been observed mainly among Alzheimer’s disease research. According to the Journal of Alzheimer’s Disease, the reduction of gamma wave in the hippocampus CA1 region of the mouse model took place even before the formation of the hallmark feature of Alzheimer’s disease, which was amyloid beta plaques. The significance of this is that there is a possibility that this could be used in future for detecting this disease much earlier than when other symptoms are detected.

This refers to studies done on animal models, but the transition to clinical diagnostics in humans is still uncertain. Nevertheless, there is sufficient consistency in this phenomenon to prompt several laboratories to consider it as a valuable early indicator.

Gamma changes related to aging also occur in healthy individuals as they age, with the common occurrence being lower gamma power and coherence levels than those found in younger people. The debate remains whether this reduction is causally linked to or just an indicator of the slowing cognitive abilities seen in aged individuals.

Can You Stimulate Gamma Waves? An Overview of GENUS Research

MIT's GENUS program — Gamma Entrainment Using Sensory Stimulation — has spent roughly a decade testing whether the brain can be nudged toward 40 Hz activity using external stimuli. The basic principle is entrainment: when the brain is exposed to a repeating stimulus at a given frequency, its neural rhythms tend to synchronize to it.

Early animal work from the GENUS lab produced striking numbers. Mice exposed to 40 Hz light flicker showed around a 50% reduction in amyloid-beta accumulation in the hippocampal CA1 region. Researchers also tested 20 Hz and 80 Hz stimulation — neither produced comparable effects. The results pointed to something specific about 40 Hz, not just sensory stimulation in general.

Combined light and sound entrainment at 40 Hz extended those effects further. Glymphatic clearance improved — the glymphatic system being the brain's metabolic waste disposal mechanism, which runs primarily during sleep and is implicated in amyloid buildup when disrupted.

Although still early in the development process, human studies have begun to confirm the direction indicated by the results found in animal studies. A Phase II study completed in 2025 found that humans with Alzheimer's disease who were exposed to 40 Hz light and sound therapy had a slowed progression of brain atrophy along with improved scores on specific cognitive tests. This research is still ongoing, but the progression from animal testing to human studies is being conducted in several research facilities.

40 Hz Gamma Waves and Red Light Therapy — What the Research Shows

Separate from the GENUS work, another research thread has been building around transcranial photobiomodulation (tPBM): using pulsed near-infrared light directed at the skull to influence brain activity. The mechanism is different from visible light flicker, but the target frequency is the same — 40 Hz.

In a preliminary study on 40 Hz pulsed NIR laser, a single tPBM session produced a significant increase in EEG gamma power alongside reductions in slower delta and theta activity. The brain's oscillatory profile shifted — not just generally upward, but specifically toward the gamma band.

The biological theory revolves around the mitochondria. Near infrared light photons, having a wavelength of 810 nm, absorb cytochrome c oxidase (CCO) present in the electron transport chain of the mitochondrion. The process results in an increase in ATP formation and energy metabolism. If energy metabolism takes place efficiently at the neuronal level, it will become easier to sustain gamma oscillations.

This distinguishes tPBM from direct sensory entrainment. The GENUS approach works from the outside in — external stimulus, neural synchronization follows. tPBM works at the cellular level first, potentially creating the metabolic conditions that support gamma activity from below. The two pathways aren't in competition; researchers have suggested they could be complementary.

Our article on photobiomodulation and cognitive function covers the cellular mechanisms in more detail for anyone wanting to go deeper on that side of the science.

Frequency, Wavelength, and Session Parameters: What the Studies Used

For anyone trying to interpret this research, a few variables come up repeatedly and are worth knowing.

Why 40 Hz specifically? Direct comparisons of frequencies have shown that 20 Hz and 80 Hz do not cause the same impact on the neurons or reduction of amyloids as 40 Hz does. This implies that the phenomenon is not linked to any kind of stimulation but rather with the fact that 40 Hz fits within the natural gamma band structure of the brain.

Wavelength and tissue penetration. Transcranial PBM therapy utilizes an infrared wavelength of 810 nanometers that can penetrate up to 20 to 40 millimeters of scalp and skull tissues. This is sufficient to affect the cortex. Red light, however, only penetrates slightly deeper into the surface of the cortex.

Session length and duration. The studies involving tPBM in humans have mostly used treatments that range from 20 to 60 minutes for up to 4 to 12 weeks. The tolerance level among participants in these experiments has been quite good, with any adverse reactions being described as transient and mild. Known contraindications involve epilepsy, photosensitive diseases, and brain hemorrhage.

These parameters reflect controlled research conditions. Real-world responses will vary, and the field hasn't yet converged on a standardized clinical protocol.

Where the Lumaflex Essential Pro Fits In

For people who are already using red light therapy as part of a general wellness routine, understanding the wavelengths and parameters involved in brain health research is useful context. The Lumaflex Essential Pro delivers red and near-infrared wavelengths — full specifications are available on the product page.

The research on 40 Hz gamma entrainment and tPBM is still developing. Anyone interested in this space is better served by staying current with the science than by drawing firm conclusions too early.

Key Takeaways

• 40 Hz gamma waves reflect synchronized, high-frequency neural activity across the brain's major cognitive networks.
• Gamma oscillations appear central to working memory, attention, and information binding — not just as a byproduct of cognition but as an active contributor.
• Reduced gamma activity in the hippocampus may precede amyloid plaque development in Alzheimer's disease, making it a candidate early biomarker.
• MIT's GENUS research has shown that 40 Hz light and sound stimulation can reduce amyloid burden in animal models and slow brain atrophy in early-stage human trials.
• 40 Hz pulsed near-infrared light (tPBM) has shown gamma-boosting effects in preliminary EEG studies through a distinct mitochondrial mechanism.
• The 40 Hz frequency matters — stimulation at 20 Hz and 80 Hz has not produced equivalent results in controlled studies.

The science here is genuinely interesting and developing fast. For a broader look at where red light therapy intersects with neurological wellness, see our pillar article on red light therapy for brain health.

This article is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare professional before starting any new wellness protocol, particularly if you have a pre-existing medical condition.