This Simple Light Hack Might Boost Your Brain Health
What if a specific form of light therapy could help clean your brain ? Well, new 2025 research reveals how this might work, and how you can take advantage of breaking science today.
What if a specific form of light therapy could help clean your brain and hopefully protect against Alzheimer’s disease? Well, new 2025 research reveals how this might work, and how you can take advantage of breaking science today.
There’s now a video covering these data as well. For those who prefer to view, see this video:
Brain Biology Background
But first, I need to arm you with brain biology background about the brain’s cleaning system: the glymphatic system. The glymphatic system is a set of channels that expand as blood vessels constrict. Imagine you have a blood vessel running through brain tissue, all bathed in cerebrospinal fluid. When the blood vessel constricts and shrinks in diameter, it creates space between the vessel and brain tissue, allowing more cerebrospinal fluid to flow through and wash away waste. I’ve already reviewed this topic with a bit more detail in a prior letter (click HERE), so I’ll refer you there if you want more.
But a big question that I left as a cliffhanger to that letter was, “How do you increase glymphatic flow and clearance of metabolic waste?”
Now… Let there be light! 40 Hertz blue light, to be more specific.
One Hertz equals one cycle per second. So, 40 Hertz just means 40 flickers per second."
Prior work has shown that 40-Hertz light flickers can improve cognition in Alzheimer’s patients and animal models. But how?
Well, returning to glymphatics—this waste removal system is impaired in Alzheimer’s disease, which means metabolic junk accumulates in the brain, including soluble amyloid particles. This can lead to a cascade of events, precipitating cognitive decline and dementia.
Now, there’s one more nibble of neuronal knowledge I need to give you before we get to the results. The glymphatic flow is regulated, in part by water channels on brain support cells called astrocytes around blood vessels in the brain. These water channels are called aquaporin 4 (AQP4) and, to put it simply, more water flow through aquaporin 4 channels allows for better flow and more rinsing of metabolic debris from the brain.
40 Hz Blue Light Enhances Cognition
The researchers exposed one group of Alzheimer’s mice to 40 Hertz blue light for 1 hour per day for 2 weeks, then testing their cognition on validated cognitive tests like a Y-maze and novel object recognition tests.
They found the blue light treatment improved memory performance closer to that of non-Alzheimer’s mice.
Shown above are Figures 1C and 1E from the paper. “WT-Con” are non-Alzheimer’s control mice. “AD-Con” are Alzheimer’s mice that did not receive 40 Hz blue light treatment, and “AD-BLUE” are Alzheimer’s mice that did receive 40 Hz blue light treatment. As you ca see, 40 hz blue light treatment restores performance in Alzheimer’s mice to levels comparable with non-Alzheimer’s mice.
40 Hz Blue Light Enhances Glymphatic Clearance
To chase the hypothesis that this improvement in cognition was related to enhanced glymphatic clearance, they injected a dye into the mice’s brains that could be traced as it drains through the glymphatic system. What you’re looking at below are data from Figures 2C and 2D. Red represents the dye in in lymph nodes outside the brain. More red, means more successful drainage and better glymphatic flow.
Let’s breakdown the Figure: You can clearly see less red in the middle panel, which represents the Alzheimer’s mice without light treatment (AD-Con, Blue Boxes), as compared to control mice without Alzheimer’s on the left (WT-Con, Green boxes). The right represents Alzheimer’s mice who were treated with 40 Hz blue light (AD-Blue, pink boxes). The upper panels represent the raw images, which are quantified in the lower panels.
If that was confusing, focus on this: There is more red (meaning better glymphatic clearance) in the Alzheimer’s mice treated with blue light (top right, pink box) as compared toAlzheimer’s mice not treated with blue light (top middle, blue box).
And, along with that, they observed decreased levels of soluble amyloid oligomers (right panel, below) that are associated with Alzheimer’s disease.
Simply put, the 40 Hz Blue light treatment made the brain better at taking out the trash!
Nuance Note 1: They did indeed show that blue light treatment increased levels of the aquaporin 4 transporter (Figure 2G shown below) that I mentioned earlier, providing a mechanism by which the blue light flicker increased glymphatic flow.
High-level Summary
Glymphatic clearance and brain cleaning is impaired in Alzheimer’s patients and Alzheimer’s animal models
This can be enhanced by 40 Hertz blue light flicker, which increases the expression of water channels (aquaporin 4) that help with glymphatic flow
And, this causes improvements in soluble Amyloid levels and cognitive performance
Nuance Note 2: Now I do say “causes” because what they did next was block different parts in the pathway, like suppressing aquaporin 4, and show this erases the functional benefits of 40 Hertz blue light flicker.
Nuance Note 3: If you really want a jargon bomb, they found this system was dependent on ventral lateral geniculate nucleus–intergeniculate leaflet (IGL)–nucleus reuniens circuit.
You don’t really need to know that. But don’t you feel smart now?
Implement 40 Hz Light Therapy Today: Gamma Light Therapy
Now, I mentioned at the beginning of the video you can take advantage of this science today. You can buy 40 Hertz flicker light bulbs and lamps. After reading this paper, I did some internet snooping for my own selfish purposes and ended up decided Gamma Light Therapy provided the all-around best spectrum of options and then reached out to the company to get a discount code for me and you. You can use my discount code NICKNORWITZ by following the link (HERE) for 15% off any products.
A Transparency Tangent
And just as a moment of transparency, for those of you interested in how brand deals like this come together, here was the sequence of events:
Last week, I got all excited reading about the new science of glymphatic regulation, which I covered in my prior letter.
My exchange with the first author, Natalie (who incidentally works in the same department as I did as Oxford for my PhD!), got me even more enthused!
Thereafter, I decided to do more digging on the topic based on tips she gave me and came across the research I covered in this video.
These data are relevant to me personally because I’m at high genetic risk for Alzheimer’s disease (ApoE4/4), and sleep is a weak point in my health routine.
So, the idea of enhancing glymphatic clearance is meaningful to me personally.
Then, after drafting notes for this video, composing the title and thumbnail, etc. on February 12th as I was flying back from the amazing Cholesterol Code Movie screener in Vegas (it was AMAZING, by the way!) I spent some flight time snooping around the internet for quality devices with reasonable price points and reached out to a couple companies.
Gamma Light Therapy seemed the best all around, and they agreed to offer us (me and you) and 15% discount.
Cholesterol Code Movie, first screening. Feb 7, 2025. Followed by CoSci conference and a 6 hour long marathon podcast between myself and Dave Feldman. Zero pee breaks!
I’m not sure if that disclosure is helpful. Let me know in the comments. But I do want you to know that 100% of the time if I promote a product, it’s because it’s one I genuinely value and would use myself or recommend to family members or otherwise think it has value for you. I hope that is received as intended, transparent and authentic.
Takeaways
So, what does all this mean for you?
Well, while this research is still in its early stages, it shines a bright light on how something as simple as flickering blue light might help protect brain health by enhancing the glymphatic system’s ability to clear waste.
If future studies confirm these findings in humans, we could be looking at a non-invasive way to support cognitive function and potentially reduce the risk of Alzheimer’s.
Of course, there’s still a lot to illuminate—but one thing is clear: our understanding of brain health is evolving rapidly, and discoveries like this could spark new breakthroughs in the prevention of neurodegenerative diseases.
Thanks! Not ApoE4, but have seen Alzheimer’s devastate my Dad, Grandmother. Dementia my Mom. I pretty much do it all to help fight against these terrible diseases of aging. Although resistance training has fallen by the wayside last 6 months. Turning that around thanks to you.
Ordered Gamma light. Nothing on website on how to use. Can I read with it? 1 hour a day is a lot unless I can multi-task.
From an evolutionary perspective why would our brain need a frequency provided by an LED light to flush itself clean? Perhaps it’s as simple as being outside under a blue sky or enjoying the sunshine reflect off a lake or river. Our brain evolved to be in the environment that earth provides us. Sometimes I think the search for the perfect experiment in a lab, takes us away from simpler holistic solutions. It’s alien that we shut older people up in a house, in a chair, and turn on a tv. They are human they need blue sky, fresh air, and sunshine. Please don’t simply add a new light bulb to the corner of their room and think their brain will work better!