Can 40 Hertz Light and Sound Support Brain Health and Glymphatic Flow?
Updated: 16 hours ago
The brain has its own cleanup system, and sleep is one of the main times it gets to work. That is why new interest in 40-hertz light and sound has attracted attention in brain health, Alzheimer’s research, and hands-on cranial therapeutic approaches.
The idea is simple on the surface: rhythmic light and sound pulsing at 40 hertz may stimulate gamma wave activity in the cerebral cortex. Early research suggests this may also support glymphatic circulation, the fluid-based clearance system that helps move waste products out of brain tissue.
That does not mean 40-hertz stimulation is a cure for Alzheimer’s disease or cognitive decline. It does mean the topic deserves careful attention, especially because it may connect brain waves, sleep, fluid movement, and cranial care in useful ways.
Why 40 hertz is getting attention
Gamma waves are fast brain wave patterns linked with attention, memory, perception, and information processing. A frequency of 40 hertz falls within the gamma range.
Recent commentary by Charles Blum, DC, discusses research suggesting that light and sound pulsing at this frequency can encourage gamma wave production in the cerebral cortex. That is notable because gamma activity may be tied to more than mental alertness. It may also influence how fluid moves through the brain.
This is where glymphatic circulation enters the discussion.
The glymphatic system helps clear metabolic waste from the brain. It is often described as a cleanup pathway that becomes more active during sleep, especially deeper sleep. This system has become important in Alzheimer’s research because amyloid plaque buildup is associated with the disease.
If 40-hertz stimulation can support gamma activity and improve glymphatic flow, it may have practical value as part of a broader brain health strategy. The key phrase is part of a broader strategy. Brain health is shaped by sleep, breathing, movement, inflammation, vascular health, nutrition, and many other factors.
How glymphatic flow connects sleep and cognitive health
Glymphatic activity appears to increase during sleep. That makes sense from a biological standpoint. The brain is highly active during the day, and it needs time to clear waste products and reset cellular conditions.
When sleep is disrupted, that cleanup process may also suffer.
Blum’s commentary points to two common patterns that can interfere with restorative sleep in older adults:
Airway compromise
Sleep apnea and related breathing problems can fragment sleep and reduce oxygen stability through the night.
Frequent nighttime urination
Urinary tract issues or other causes of waking to urinate can repeatedly interrupt deeper sleep stages.
Both patterns may reduce the time spent in sleep states that support healthy brain rhythms and fluid movement. That may matter for people concerned about memory, cognitive changes, or neurological aging.
This does not mean every sleep problem leads to cognitive decline. It does mean sleep quality should be part of the conversation whenever brain health is the concern. A device that provides 40-hertz stimulation may be interesting, but it should not distract from identifying treatable sleep disruptors.
What 40-hertz light and sound therapy may look like
Several types of tools are being explored for home or clinical use. Some use eyewear that flashes light at 40 hertz while headphones deliver matching sound. Others may use screen-based activities, such as memory games or puzzles, paired with a 40-hertz flicker and tone.
In theory, this creates rhythmic sensory input that the brain can respond to. The hope is that repeated exposure may help support gamma wave activity and glymphatic circulation.
For cranial therapeutic approaches, the idea is especially interesting. A practitioner may use 40-hertz light and sound during cranial treatment, or suggest it as part of home-based brain rehabilitation exercises.
That said, comfort matters. Flashing light can be unpleasant for some people. Sound sensitivity, headaches, dizziness, visual discomfort, and fatigue should all be taken seriously. Future devices will likely need to be easier to tolerate if this approach becomes more common.
The promise of 40-hertz stimulation is not that it replaces sleep or clinical care. Its promise is that it may add a low-burden way to support brain rhythms and fluid clearance when used carefully.
Where cranial therapy fits into the picture
Cranial therapeutic work often focuses on subtle motion, tissue tone, fluid movement, and nervous system regulation. The glymphatic system gives practitioners another reason to think about the brain as a fluid-dynamic system, not just an electrical or structural one.
If sensory stimulation at 40 hertz can influence gamma activity and glymphatic flow, it may pair well with approaches that already aim to support cranial function. For example, a session might include calming manual care, attention to breathing patterns, and carefully timed exposure to light and sound.
Still, this area is developing. Clinicians should avoid overstating the evidence. Patients should not be told that 40-hertz stimulation prevents Alzheimer’s disease or removes amyloid plaques. The more accurate message is that early research suggests a possible supportive role, and more study is needed.
A cautious clinical approach would include:
Screening for seizure history or light sensitivity
Asking about migraines, vertigo, and visual discomfort
Reviewing sleep quality and possible sleep apnea symptoms
Starting with short, tolerable sessions if appropriate
Coordinating care with the patient’s medical team when cognitive decline is present
The mention of epilepsy is especially important. Flashing light can trigger seizures in some people with photosensitive epilepsy. Anyone with a seizure history should avoid this kind of stimulation unless cleared by a qualified medical professional.
This article is for informational purposes only and should not be used as medical advice, diagnosis, or treatment.
The practical takeaway
40-hertz light and sound is a promising area of brain health research because it may connect three important systems: gamma wave activity, glymphatic circulation, and sleep-based brain cleanup.
For cranial therapeutic approaches, it opens an interesting possibility. Gentle sensory stimulation may one day become a useful companion to hands-on care and home brain exercises. For now, the most responsible path is cautious exploration, careful screening, and honest expectations.
The basics still matter most: protect sleep, address breathing problems, investigate frequent nighttime waking, and seek medical guidance for cognitive changes. If 40-hertz tools are used, they should support those foundations rather than replace them.
Citation
Blum C, DC. Forty-hertz light and sound, gamma waves, and increased glymphatic circulation: Implications for cranial therapeutic approaches: A commentary. Presented at the 2025 SOT Research Conference, 2025.
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