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Does listening to a 40 Hz tone “clean up” the brain in Alzheimer’s patients?

In 2012, I made a Web-based tone generator with the goal of helping tinnitus patients determine the frequency of their tinnitus to better target therapy. Since then, I have heard from people using my generator to teach physics, practice violin, drive away carpenter bees, tune DIY speakers, analyze room acoustics, calibrate vintage synthesizers, cause mischief in class with frequencies the teacher can’t hear, and even open a portal to Sedona, AZ. Far be it from me to take away from all these worthwhile applications, but last week, I got a message from Dennis Tuffin (of Devon, England), describing a new use for my generator which may very well trump everything else:

For the past 7 weeks I have been using your tone-generator for a purpose I wouldn’t think you had envisaged but about which I am sure you will be interested.

I have been following up on some research which my daughters had done about the treatment of Alzheimers by using a 40Hz flickering light source or alternatively a 40Hz sound source. There is sparse info on the net about these experiments though there is a recent piece about it. [here Dennis is referring to this paywalled article]

So I have been trying the sound therapy on my wife who is in the advanced stages of Alzheimer’s and to my surprise after 8 days she started to show small signs of being more mentally alert than before. So I have continued to use your tone generator using a 40Hz sine wave for about an hour each day. (I’ve recently started to do it twice a day for slightly shorter sessions). I found it necessary to connect external speakers to my laptop in order to pick up such a low note and to run it at a level of between 46-54 decibels so that she hears it wherever she is in the room. (Dementia sufferers get very fidgety!). So now 7 weeks on the improvement in her awareness has continued to the point where she is starting to be able to put a few words together and to respond to questions neither of which she has been able to do for nearly a year. Her odd physical habits have not been changed so far but she is definitely walking better and not shuffling her feet as she used to. Surprisingly, she is also sleeping better and not suffering as much with the sleep apnoea problem that she’s always had.

Photo of laptop and a small speaker on a kitchen countertop

The setup used by Dennis. The black box on the left is the external speaker.

Of course I expect there to be a limit to this progress as in the 8 years since my wife was first diagnosed her brain will have shrunk considerably so I do not expect her memory to return but on the other hand my wife’s quality of life has been improved.

To date I have not gone public on this and only close family have known but by the end of another week when it will be 8 weeks since we started I think I would like to spread the word and hopefully prompt a few professionals to do more proper research.

The science so far

  • It has been known since at least the 1980s that cognitive activity triggers brainwaves (wave-like patterns of activation) at a frequency of 40 Hz in humans and other mammals.
  • In 1991, researchers from the NYU Medical Center discovered that Alzheimer’s patients have reduced 40 Hz brainwaves compared with healthy people. (paywalled paper)
  • In 2016, MIT’s Alzheimer’s group did experiments on transgenic mice with early Alzheimer’s disease and found that exposing them to a light flickering at a frequency of 40 Hz (40 times a second) for 1 hour a day for 7 days causes an almost 60% reduction in β-amyloid plaques, which are a molecular hallmark of Alzheimer’s. Flickering at 20 Hz and 80 Hz did not have the same effect. An important qualification here is that the effect was limited to the visual cortex, which is not significantly affected in human Alzheimer’s patients. Here’s an accessibly written report in The Atlantic and here’s the original paper (published in Nature) if you’re strong in science-speak. MIT also made a video about the findings.
  • In March 2016, scientists at the University of Toronto published the results of a small, placebo-controlled pilot study (paywalled paper), in which they exposed 20 Alzheimer’s patients to a 40 Hz sound. After six 30-minute sessions (done twice a week), the patients’ average score on the 30-point SLUMS scale improved by 4 points, while the placebo group did not improve. It should be noted that the “dosage” of the treatment was rather low, which may explain the modest results.
  • In January 2017, Cognito Therapeutics, a company formed by some of the members of the MIT team, started conducting preliminary trials to assess the safety of exposing AD patients to simultaneous flickering lights, an audio tone, and vibrations – all at 40 hertz.
  • In January 2018, the New Scientist reported (paywalled article) that the same MIT team achieved even better results by playing mice a 40 Hz sound. β-amyloid plaques shrank by about 50% in the auditory cortex and – crucially – in the hippocampus, perhaps because the two areas are close to each other. This would be a very important discovery, because the hippocampus is the region of the brain which is involved in forming memories. It is the hippocampus that suffers the most damage in human Alzheimer’s patients. According to the magazine, these results were presented at the Society for Neuroscience conference in Washington in November 2017. However, the published paper described a significantly different protocol (see below), so it is likely that the New Scientist didn’t get the details right.
  • In July 2018, the International Journal of Alzheimer’s Disease published the results of a pilot study in which 6 human patients were exposed to a 40-hertz flickering light bulb for 2 hours a day for 10 days. The therapy was administered in a home setting by the patients’ caregivers. No difference in β-amyloid plaque was found after therapy. If there was an effect, it must have been smaller than 20%, which is not comparable to the 50% reduction seen in mice.
  • In March 2019, Cell published another (paywalled) paper about another study done by the MIT group. Here’s a NYT article about it. Here are the main points:
    • After mice were exposed (for 7 days, 1 hour a day) to a series of clicks repeating at a frequency of 40 Hz, the amount of amyloid plaque in their auditory cortex and their hippocampus was reduced by about 40%. The mice also did better on several tasks involving the use of memory.
    • The clicks were 10 kHz waves, 1 millisecond long, repeated 40 times a second (each cycle had a 1 ms tone followed by 24 ms of silence). In communication with me, one of the paper’s authors said that pure 40 Hz tones were not used because mice cannot hear tones of such a low frequency.
    • When this auditory treatment was combined with light pulses at 40 Hz, microglia (“brain cleaner cells”) started clustering around amyloid plaque, and the reductions in plaque extended to parts of the prefrontal cortex (an area related to functions like attention and short-term memory). This effect was not observed with either audio or light treatment alone.
  • In 2018, Cognito Therapeutics started three clinical trials of their device (called “GammaSense”) that combines visual and auditory stimulation. The device is essentially LED goggles with over-the-ear headphones.
  • [NEW] In 2019, Dr Tsai’s MIT group started two small trials of another device – a white screen illuminated with LEDs flashing at 40 Hz combined with a soundbar emitting a 40 Hz “buzzing” or “humming” sound. Here is a summary of Dr Tsai’s presentation on it and here are the pages for the two trials on
  • [NEW] In April 2021 at the AD/PD conference, Cognito presented preliminary results of the GammaSense trials, most notably, the Overture trial (news story from, which is designed to evaluate efficacy. 46 patients with Alzheimer’s Disease received a daily 60-minute session with the GammaSense device for a period of 6 months. The control group comprised 28 patients who received sham treatment (i.e. a placebo-like device that isn’t supposed to do anything). The study seems to tick all the boxes for good scientific research: it’s randomized and multi-center. Although it’s not strictly double-blind, the subjects, their caregivers and the people who rated the patients’ cognitive functions were blinded (i.e. they did not know who has received real treatment and who the sham). Back when this trial was announced, I wrote that it was rather small and the only way it could show anything is if the device had a large effect. Well, the results are decidedly mixed, and I can pretty confidently say that GammaSense didn’t have the sort of huge effect everyone was hoping for. There was no significant difference between GammaSense and placebo on 3 out of 5 cognitive tests used in the study, and GammaSense came out slightly ahead on two of them. Brain tissue loss also seemed to be slower in the treatment group, though that doesn’t have to mean anything, considering that the control group was older than the treatment group. I would definitely like to see a proper, peer-reviewed paper rather than just a presentation – someone should go over Cognito’s work and make sure the results are statistically valid. The researchers collected amyloid PET scans, CSF, and blood samples, but have yet to analyze them. I do like the fact that cognitive function was assessed, not just amyloid deposits – we already have experimental drugs that remove β-amyloid, but don’t do anything when it comes to actual dementia. Too bad the results have fallen short.
  • Cognito is not giving up and has announced another, larger study, which is to start in the second half of 2021.

Further reading/listening

Update from Dennis (March 2020):

I’ve gotten in touch with Dennis Tuffin to ask about his long-term experiences with 40 Hz therapy. Here is his response:

I reached a point when I knew that my wife’s condition was worsening so after [about 8 months] I gave up using the sound treatment. (…) My wife was already losing verbal capacity and was decidedly becoming slower in her movements, so it’s not the case that stopping the treatment caused these things as they were already happening. I was enthusiastic about it, because there appeared to be a noticeable improvement in her capabilities for that 8 or 9 month period, so noticeable that it was remarked on by almost everyone that she knew. So I am still sure that it helped, if only for a limited period and I think that it’s also likely that if it had been applied from the beginning of her diagnosis it may have had an even longer lasting effect. I’d still say give it a try – it costs nothing.

Dennis also told me that he had recently learned that his wife has vascular dementia in addition to Alzheimer’s Disease. I mention this, because that fact might have some bearing on the effectiveness of sound therapy.

(Don’t) try this at home

Let’s say you are not dissuaded by the lukewarm results from the Cognito trials. You’ve decided that you’ve got nothing to lose and you want to try some kind of do-it-yourself auditory therapy. What kind of tones should you use?

Dennis, the reader from the UK who piqued my interest in this subject, used a pure 40 Hz tone.

According to this AlterNet article (later reprinted by The Salon), a pure tone was used in the preliminary safety study done by Cognito in early 2017.

It appears that the most recently published MIT study on mice used series of clicks (despite previous reports) rather than tones. The New York Times quotes Dr. Tsai, who worked on that study, as saying “your brain seems to be able to perceive clicks more than a tone”, which would seem to indicate a preference that’s not exclusive to mice. However, in response to my inquiry, another co-author of the paper, Ho-Jun Suk, said that 40 Hz pure tones were not used because mice cannot hear tones of such a low frequency.

The New York Times and the Boston Globe published articles about the MIT mice study, including links to audio samples of the stimuli that were used by the researchers. Unfortunately, I have discovered that neither sample represents accurately the audio waves that were played to the mice. The clicks in the published samples are smeared in time (closer to 2 ms) and are not pure 10 kHz tones. Ho-Jun Suk has confirmed that they do not match the source signal. (I don’t know how the NYT and Boston Globe managed to mangle the files so badly, but it’s not because of compression – I tried it on the same encoder and the same parameters that were used by the NYT and it did not distort the signal very much at all.)

This 2021 report from Alzforum uses the words “hum” and “buzz” (interchangeably) to describe the sounds used in the two ongoing MIT trials of the screen+soundbar device. This would seem to indicate that those trials use a pure 40 Hz tone, as a series of clicks doesn’t sound like humming or buzzing. Furthermore, it is reasonable to assume that if the researchers wanted to play a simple series of clicks, they would have used a smaller and more economical speaker, not what is described as a “high-fidelity soundbar”. However, the same article uses the word “buzz” when discussing the 2019 mice study, and we know that one used clicks, not tones, so we should be careful about how much we infer from the phrasing in that particular report.

If you are thinking about using clicks rather than pure tones, I would not recommend using 10 kHz clicks because human ears are not very sensitive to that range of the spectrum. Something like 3 kHz (where human hearing works the best) would probably be more sensible.

It would be very interesting to know what sort of tones are being used in the now ongoing human trials. (If you are in the trials or know anyone who’s in them, please let everyone know in the comments section.)

Technical advice for playing pure 40 Hz tones

A series of clicks is not particularly demanding – it can be played on anything. If you want to try playing a pure 40 Hz tone to someone with Alzheimer’s, here’s some technical advice:

Getting a 40 Hz tone is easy – you can use my frequency generator. (Please note I do not take responsibility for the purity of the produced tone, as it is generated by your Web browser – though I think it should be fine. By the way, I am also not a doctor and I am not giving medical advice or offering any medical product here.)

You will need decent speakers. 40 Hz is a very deep bass tone – the kind of rumbling tone that you feel in your body as much as you hear it. Small speakers, such as laptop speakers or small computer speakers, don’t go that low. If you try anyway, you will either hear nothing, or you will hear mostly – or only – distortion. What is distortion? It’s a higher-pitched, buzzing noise that speakers make when you push them too hard.

Photo of a bookshelf (monitor) speaker

A bookshelf speaker (photo: D. Cedler)

Bookshelf speakers will do 40 Hz, but their output at that frequency will be significantly reduced, so you will need to turn up the volume significantly, and they will produce easily audible distortion. Because the ear is more sensitive to high frequencies, the distortion may be subjectively louder than the fundamental 40 Hz tone (!), and may make the sound harder to tolerate, thus limiting the volume (and possibly the therapeutic effect).

The best solution is a high-quality subwoofer. It won’t be distortion-free, but you can expect the distortion to be 2–3 times quieter than with bookshelf speakers. This will give you as pure a tone as you can get. If you don’t care about playing music, you can get just a subwoofer (without any other speakers) and connect it to your computer or mobile device.

A neat trick to amplify the bass output of any speaker is to place it against as many walls as possible. For the maximum boost, put the speaker(s) on the floor, in a 3-way corner between two walls and the floor – that way, it will be adjacent to three surfaces.

How important is sound quality? It’s hard to say. Dennis seems to have had great results with cheap computer speakers. It is not known to what extent the therapeutic effect depends on volume or the presence of distortion. On the other hand, if you use small speakers, it won’t be obvious whether they’re actually playing 40 Hz or just distortion – so it’s worth getting something bigger just to be on the safe side.

Can you use headphones instead? It’s hard to say with certainty, as a 40 Hz tone played through your speakers will not just be heard with your ears – it will also be felt in your whole body. With headphones, the effect is strictly auditory. However, so far I haven’t seen any specific scientific reasons to suggest that this difference is important, and in fact headphones were used in the initial safety studies commissioned by Cognito. If you decide to use headphones, make sure they can do 40 Hz. The earbuds that came with your smartphone are probably not the way to go here. HeadRoom has a database of frequency response graphs for high-quality headphones, so you can check how loud a given model is at 40 Hz. Want a specific recommendation? Get the Koss Porta Pros (, They’ll do the job, they’re the most comfortable headphones I’ve used, and – at $40 – they’re tremendous value.

Call for comments

If you or your loved one has Alzheimer’s disease and you have tried 40 Hz sound therapy, please share your experiences – whether positive or negative – in the comments section below.

180 Comments so far

  • Jeff

    Just a comment regarding LED lighting and incandescent lights. The LEDs can turn on and off in microseconds, thereby actually creating pulses of light, going on and off 40 times per second. The 40 hz sound wave, using your oscillator, is typcially a sine wave, very different effect than pulses. There is sound at increasing and decreasing levels except for once every 0.0125 seconds when the signal crosses through zero. I am wondering if incandescent lights at 40hz would better, as the filament goes from light to not quite dark similar to a sine wave. Almost like using a dimmer switch up and down, rather than an on/off switch.

    Were any experiments done with incandescent lighting at 40hz or with true PCM output voltage to LEDs?

    • Robin Elliott

      Tomasz – I am currently trying to taper off benzodiazepines prescribed by my doctor for sleep. You may not know anything about benzos but they should be illegal as they cause injury to the brain and one of the results is loss of memory and even dementia soo am very interested in the use of 40hz to possibly help heal my brain and ward off dementia. I have tried listening to the 40hz clicks vs the 40hz tone that you made and I cannot tolerate the clicks at all using my headphone with my iPhone. I get dizzy and beryls uncomfortable even after just a few minutes. The tone, however, feels wonderful. Has anyone else observed the same thing? Also, since I have an I phone, the headphones you recommended do not work with it. Do you recommend another headphone for I phones? Thank you

      • Sal

        Try the “Amazon Basics” headphones which do reach 40 Hz quite effectively. They have surprising sound quality, a hint that they may be culls from expensive driver production lines.

        * Cheap, approx $15/pr and the plastic head piece often breaks. Don’t stress the head band. They can sometimes be taped back together and work OK.

        * Very comfortable with puffy leatherette cushions for a good seal on the ears.

        * I use the “sawtooth” tone, which have an ‘attack’ that most closely approximates pulses.

        * Don’t have enuff hrs logged on them yet to be definitive, but my sessions run 15 to 30 minutes, several times per week. My memory seems to be improving, subtly. Here’s hoping.

      • Doug Cutler

        I began using 40Hz therapy almost two years ago specifically to help with chronic acute insomnia. (We know disrupted sleep is a major risk factor for old age dementia.) Though anecdotal, I can report that in my experience it seems to be very beneficial. I’ve also had experiences with prescription hypnotic pharmaceutical drugs similar to your own. These are seductive and dangerous drugs. I don’t go near them now.

        Also, I take a shot gun approach to sleep: vigorous exercise, blue blocker sunglasses for late night screen time, sleep mask, melatonin, tryptophan, magnesium, chamomile, meditation to clear the day’s thoughts and emotions and to slow brain waves, etc. But I’ve found 40Hz therapy seems to have really tipped the balance towards better sleep.

        Look for a more intensive write-up of my 40Hz experience in this thread.

        • Tomasz P. Szynalski

          How exactly are you using 40 Hz sound for sleep? Do you fall asleep with headphones on?

          • Doug Cutler

            Yes, I actually sometimes fall asleep with the headphones on and sometimes blasting at pretty high volumes. It’s a seeming paradox that fascinates me. I think there may be some brain plasticity involved and my brain has gotten used to sleeping with the 40Hz over time. I’m not sure someone else could just go to high volume 40Hz sleep from scratch.

            So here is how I got there, my history with 40Hz:

            My first experience with was about two years ago. 8hrs sleep the first night. I was thrilled. But it was short-lived.

            At the time, I was experiencing chronic acute insomnia. It’s something hard to describe to those who have never been through it. Night after night of 1,2, or 3 hours sleep in spite of laying in bed the whole time. The feeling of being too exhausted to sleep. Learning the difference between mental anxiety which is controllable to a degree and body anxiety which is much deeper. I really felt my whole sleep chemistry was out of whack. I was in my mid-sixties and worried about the risk of dementia in the years ahead from the disrupted sleep.

            So after my first night of great sleep I followed up with return to a week of bad sleep. So I decided to up my game and began combining 40Hz light AND sound.

            About a week after 1 hr/day of the light and sound – usually before or after supper – my sleep began to improve. Since that time my sleep has been much improved over all. Not perfect . . . but I no longer fear the long night, no longer feel trapped in sleepless hell. I still get the occasional bad night but these are usually isolated and I catch up the next night. That I can cope with.

            So for the first 6 months I did my 40Hz during the day but these days I combine it right into my sleep cycle. I discovered this by accident. One night about a year ago I was having a particularly bad night, 4am and still no sleep. So I thought to myself “if I’m not going to sleep maybe I can still get a little brain cleansing from the 40Hz, at least that might be some help.” So I put on the full 40Hz light and sound right in the middle of the night. Thing is I didn’t last 20 minutes. The 40Hz knocked me right out. Of course, my eyes closed to the lights but my 40Hz head phones were still up pretty cranked yet I still slept through.

            You must also know I’m rather keen on the research suggesting the greater to 40Hz intensity the greater the brain response. So my normal mode is the 40Hz string little LEDs Christmas lights strung out on a wire screen and planted directly in front of my face. (Also, I always use blue blocker sunglasses because the lights are a bit on the bright white side.) Then I use over ear ear head phones for the audio with sound turned up pretty high like maybe 70-80 db. At this level I can also feel some 40Hz vibration as well. That’s the plan, overwhelm the brain with 4oHz stimulation. I get my 40Hz audio off YouTube but I prefer one sight in particular because the wave form seems to have a bit more edge or bite. Not sure but perhaps it’s a more jagged square wave pattern as opposed to the smoother sine wave.

            So now, I have everything set up at beside ready to go. Lights are on a boomed mic stand I can swing in front of face on the pillow and YouTube 40Hz ready to go with the headphones. Typically these days I will fall asleep for an hour or so and then wake up unable to fall asleep again. So then I just put on the 40Hz. 90%+ of the time I’m back to sleep in 20 minutes or less. Very occasionally I will last longer but then am able to return to sleep. I think in the last year I’ve had maybe 3 or 4 nights where the 40HZ seemed to have no affect.

            Sometimes in the early morning I will wake up again and then I will do 40Hz sound only except with the sound way down. Often, this will get me an extra hour or two of sleep in the morning.

            There is some evidence in the latest research indicating sleep benefits from the 40Hz. In some ways, this result might be more clear than the results for a reduction in cognitive decline. Nevertheless my report here should be taken as anecdotal. These may be experiences unique to myself. Nevertheless, I think the improved sleep connection is one the researchers should take very seriously.

            • Tomasz P. Szynalski

              Very interesting. Thank you for the detailed writeup and I’m glad your protocol works for you so well. It would be interesting to find out if there’s really something special about 40 Hz or perhaps something like this would work just as well. Personally, I think I might find a 40 Hz tone too distracting to sleep – it sounds like a running engine next door. Furthermore, it’s possible that your sleep cycle is misaligned (you try to go to sleep too early with respect to your circadian rhythm). It can be shifted with rigorous application of light therapy and (optionally) melatonin. See this guide. You’re clearly a very methodical fellow, so it might work for you. Unlike 40 Hz, using light and melatonin actually has some scientific foundations. But we’re going off-topic for this post…

            • lisa power

              The sleep connection makes sense as we now know that brain ‘nourishing and cleaning’ occurs at night; that this is at least one function of sleeep; and that 40hz triggers activity of glial ‘cleaning’. I too do it at night before sleep (for that reason), audio only, and it often ‘knocks me out’ pretty quickly as well, and I usually have a solid night of sleep. I had brutal insomnia for years from stress (until receiving stress treatment I had no idea being a cortisol monkey could truly damage the brain to the extent it does.) So I feel for you.

          • Doug Cutler

            One other detail: I’m a side sleeper so for sleeping with over ear or around ear head phones I have a regular foam pillow into which I’ve carved out a cavity with a razor knife large enough to accommodate the headphones without pinching my ears.

            • Kevin Van Den Broek

              Hi, I put together some components with a 555 timing IC and dialed it in to 40hz (Square wave) using a frequency counter and plugged my head phones into it. I had no idea what I had stumbled onto as I made it for some background noise to meditate with to drown out the pain-full neighbors.

              I used it last night and after about 30 seconds I was out to it and woke up 2 hours later with a start wondering what had happened. so I looked up the frequency on line and found your web page. Thanks for the info.

    • John Falcatan

      I’m using a fan. Simple. The hard part is calibrating the rate.

      Before, I used a 555 IC chip, then a series of 8250s (? not sure of the exact IC series….)to drive the led. Worked nicely. Calibrated it with a speaker and tuned it to that low Eb (approx).

      The fan will work best once I find the engineering student to calibrate it for me. Or study up myself. Meanwhile, I’m listening to 40 Hz signal at szynalski’s.

      Sounds great. You did read up on the Buddhist monks who have very strong Gamma when meditating……

      Best of luck! JF. .

    • Doug Cutler

      In my own experience, I prefer ‘edgier’ square or triangular wave forms for the audio. My own non-scientific ‘hunch’ is they register more easily in the brain thus resulting in more efficient brain wave entrainment. I find sine wave 40Hz too smooth.

      I also think louder is better. Brighter is better for the lights as well. I have the string of 40Hz mini-LEDs strung out on a wire frame and planted right in my face. I use 40Hz for sleep and so far it seems effective. Purely an anecdotal report, of course.

  • Mark

    Dear everyone,

    I am touched to read about so many personal stories.

    I highly recommend to try a neurofeedback training, in case you are looking for alternative and stronger options. I personally have very good results in treating burnout, and both my parents are starting in the short term.

    Next to training the brain to have more capacity, training for more gamma waves specifically would also be an option. This training is permanent and much much stronger then just audio signals. In my first session my 33 year old brain brain could only handle 14 minutes 🙂

    Then also to bring this on everyone’s radar, the Bredeson protocol seems to be very promosing in treating alzheimer. It regards and treats Alzheimer as a muli-factor lifestyle disease – with the ketoflex diet being the most important intervention.

    Kindest regards,


  • Roy

    Hi, Tomasz:

    I got the idea to try the 40Hz from a TED Talk called:

    Music Medicine: Sound At A Cellular Level

    I tried putting the link into the comment, but your system rejected the message.

    I have old-school 12″ 3-way speakers, so producing a clean 40Hz tone is no problem.


    • Rob

      I wanted to add this information for people dealing with, or helping someone with dementia:

      The speaker in the TED Talk you mention, Dr. Lee Bartel is (Professor Emeritus of Music at the University of Toronto) has helped develop a device called a vibroaccoustic therapy system. It looks like the backrest of a chair and it has built-in speakers (in an interview also available on youtube Dr. Bartel says it is like “sitting on a subwoofer”). It has four tracks of music integrated into it and also has an input where you can connect an external device to listen to, and feel the vibrations of, other sounds or music. Dr. Bartel and others at the University of Toronto have conducted research using 40 Hz. gamma sound and vibratory stimulation to treat Alzheimer’s, among other diseases. I was researching the work of Dr. Tsai at MIT when I came across an article related to the University of Toronto research titled “How flashing lights could treat Alzheimer’s disease,” available at this link:

      This article discusses the work of a colleague of Dr. Bartel, Dr. Amy Clements-Cortes; in the article she mentions a patient with early signs of dementia who used a device at home for three years and whose cognition stayed the same during that time. Interested, I contacted Dr. Clements-Cortes to inquire whether the device is available to consumers. She said it was, and she asked whether we were interested in taking part in a study using the device (I am helping to care for a relative with clear symptoms of dementia but with no pathological diagnosis). I purchased the device and we began using it in the eight-week study six weeks ago. Unfortunately I can’s say much as to the efficacy of this device yet. But my relative does seem eager to do the 30-minute sessions. We definitely intend to continue using the device after the study ends, and we are thinking about adding 40 hz flickering light if there are no contraindications.

      To my knowledge, it is still possible to take part in the study. Anyone interested can contact Dr Clements-Cortes. I had to purchase the sound system myself, but was provided with the “treatment track” of 40 Hz gamma sound. I was planning on buying the device anyway after reading the BBC article.

      The vibroaccoustic therapy system is produced in the U.S. by a company called Sound Oasis. The model nuber is the VTS1000. (Price: $499.00). The treatment track I mentioned is also available for purchase on Sound Oasis’s website.

      Anyone who is as interested as I was in this device might find this pdf (“New Hope for Alzheimer’s” by Dr. lee Bartel)– which I just found the same day I found Tomasz’s excellent blog — useful:

      Best Wishes,


      • Tomasz P. Szynalski

        Excellent research. Thank you for posting all this information. I haven’t read all of it yet, but one big takeaway from the BBC article (if it is accurate) is that Dr. Tsai uses a series of clicks rather than a 40 Hz tone.

        • Rob

          Yes, that I what I understood from the article. I also read somewhere else (I do not recall the source) that Dr. Tsai theorizes that clicks might be more effecive than just a tone at 40 Hz.

          In the link at the very bottom of my comments above, Dr. Bartel mentions small studies using 40 Hz. sound, vibration and light in combination. The results have been very positive, but, the number to participants has very been small.

  • Jay

    This is very intriguing to me and wondering if there are known benefits playing 40Hz beyond improving the effects of Alzheimer’s. Is/are there potential benefits or risks to healthy individuals?

    Best, Jay

    • jenni

      i watched the video on youtube about this. he said he got the idea from listening to crickets tune themselves to the same beat as a squeaking belt. he said that 40hz didn’t just help alzheimer’s but also helped a woman with fibromyalgia get off of all of her medications. i also have fibro and it’s why i’m even here on this website. the idea is that your body works in the area of 40-100hz and if you listen to the sound somehow your body begins to tune itself to the same frequency. this would help all neurological disorders in my opinion since it is changing the waves of the brain to be back in tune. he said it would not help a person to recover their minds as to what has already been lost but that there is no more deterioration during the period of using the tones in alzheimer’s. however with fibromyalgia there seemed to be a more complete recovery since she no longer required medication for the symptoms.

    • jojo

      In Frequency Specific Microcurrent therapy, 40 Hz is used for lowering inflammation.

    • Nicholas Keller

      Well, subclinical levels of abnormal protein aggregation as occur in everyone could well be part of cognitive decline.

  • Bill

    I’ve been using 40hz sine wave with headphones for 3o minutes a day three times a week for a couple of months. I don’t have Alzheimer’s. I can say I can now remember things – like the name of a backup helicopter pilot I once flew with in the 1980’s – that I’d not been able to recall previously. No idea if that’s correlated or caused – but I plan to keep this up and see what happens. It can’t hurt anything!

  • Selasie Agbavor

    And here I was, thinking I was the only one in the world thinking in this direction. Very intriguing work. Greetings from Ghana.

  • Jeremy

    I suggest that instead of using 40 Hz tones (too low for most speakers to produce or old people to hear) or clicks, you use beat frequencies. These have been used in brainwave entrainment for a long time. To get a beat frequency of 40 Hz, just play 2 tones that are 40 Hz apart in frequency, e.g. a 440 Hz tone and a 400 Hz tone.

    For best results, use tone that are easily audible and below 1000 Hz. Most research has been done with headphones, playing one tone in one hear and the other tone in the other ear, but it is not clear that that is necessary, as effects can be observed just listening to the tones playing together on a normal stereo without headphones.

    Google “Binaural Beats” for a lot more information.

  • Steve

    I have made a 40hz sine wave and synchronized 40 Hz LED glasses (blue LEDs)

    I am currently ‘testing’ on my father-in-law, after 1 week of 1 hour a day sessions he and others have noticed improvements. He is no longer sleeping during the day and his mood has improved, he seems more alert. We will continue to test the device on him.

    If anyone is interested in a device, I can make them to order (UK).


    • Clif Davis

      Hello Steve!
      I am very interested to discover that you can build a product that may help me with my brain. Can you send me any data about what you have to offer ?
      Thank you very much!
      (I do understand that any experimentation I choose to do on myself …is of course my own decision and my responsibility)

    • Katrina

      Hi Steve,

      I’m interested in getting one of your devices. Please let me know how I can get one. I’m in the US.

      Thank you

    • Paul Brown


      I’m in the US. My wife’s uncle has alzheimers and may be able to benefit from your device. Would you please send me more information on aquiring or building one? Thank you.


    • Melisa

      Hi Steve,

      I am interested in knowing more about your product.

      I am UK based and my father is suffering from memory issues after 3 strokes. I am also studying music for healing, and really interested in. new technologies related to sound and vibrational therapy.

      Look forward to hearing from you,

    • Zohaib

      Hi Steve – I would be very interested exploring the device you made for my family. Please let me know as I am in the US but also have family in the UK.


    • Aylene Bowman

      I just saw your post from some months ago in the archives. Are you still making the 40 Hz sound and LED glasses? If so I am interested. I live in Australia so hope you wouldn’t mind sending them Downunder. Please let me know if you could make me a pair of the glasses. Cheers,


    • William

      Hi Steve,

      I would also be interested in purchasing your device. I am in the US, but would be glad to pay for extra shipping.


    • Keith

      Hi Steve
      Keith here and I am interested in the device you have made to help improve the memory.
      Could you kindly send on further Information?

      Thank you Steve.

    • Rob

      Hello Steve,

      Are you still making the 40 Hz LED glasses? If so, please send me the details on how I can order them from you.



    • Kathy

      Hi Steve,

      I, too, am interested in buying one of your devices. My 92-yr-old father has been showing signs of mild cognitive impairment (MCI) over the past year and may be in the early stages of Alzheimer’s.

      If you’re still making these devices, please send me information about how to purchase one. I’m in the US and would be more than happy to pay extra shipping charges.

      Thanks in advance (and crossing my fingers…!),

    • Victoria

      Steve, how much do you charge for the device? I’m in the the US. I have early onset dementia, and am motivated to slow the progression.
      If the UK to US shipping (and electric plug) make it impractical to sell to me in the US, perhaps you could share info and my husband could build it for me? Thank you!

    • Kim

      Hi Steve, I’m checking in to see if your father-in-law still continued to get benefits from the device you made. I’d also like to know if I could pay you to make a device for me. Thanks!

    • Garth E Fisher

      Hi Steve, if you are still making the glasses I am interested in getting one, I have a David Delight that uses LED light, but not the way you are describing, thanks, let me know Garth

  • Don Mallik

    Do you have an opinion or information on this:
    Must you actually “hear” the 40 hz tone to be effective? My hearing is zip in that range.

    • Tomasz P. Szynalski

      Nobody knows if this thing works on humans, but if I were to speculate, my guess would be yes, you need to hear it to get the effect in the auditory cortex (and neighboring areas).

      • Patrick VeVea

        I am not convinced one needs to “hear” the tone. I wonder if the vibrations may be enough to, or are the actual substance of the change. I have not seen any indications as to what volume these tests are being conducted at. For the hearing impaired maybe try playing this frequency thru a home audio sub-woofer system at louder volumes?

        Also, is it possible that just because we don’t recognize that we can hear this frequency our brain isn’t still processing it?

        • Gillian R

          I think you’re right. You know when you’re travelling and the bus juuust has the right engine vibe to soothe?

    • Doug Cutler

      I like to use over ear headphones for 40Hz therapy and set the volume a little loud to where I can also feel some of the 40Hz physical vibration as well. I find the sensation rather soothing like a fast cat’s purr running through my chest and spine.

      There is also some speculation the 40Hz vibration is worth studying as a therapeutic delivery mode. There is even some discussion elsewhere in this thread about an elctro-acoustic system for delivery of 40Hz and other frequencies. You might track it down.

  • Samantha

    I used audacity to make a click track with 1ms pulses every 25ms. Can you check it fits the researchers’ specs after being compressed for mp3 etc.?


    • Mikko Rantalainen

      Samantha: it seems that MP3 compression is going to destroy your waveform. Also, the click should start and end with a short fade to avoid high frequency artifacts. I guess FLAC should be able to compress the final audio track very well.

  • Samantha

    Ah! I just realised…”The clicks were 10 kHz waves, 1 millisecond long, repeated 40 times a second (each cycle had a 1 ms tone followed by 24 ms of silence). ”

    10 Khz would be 0.1ms long right? 1Khz would be 1ms long, i.e. 1000 every second, but 10Khz is 10,000 every second.

  • Michael

    I have been using the 40 hz tone to treat my wife. We both tolerate the sound very well. It is not offensive at that low frequency. I have old school speakers with 12 woofers with 5 lb magnets. It makes a very clear good sounding sine wave. I bought a strobe light and ripped out the pcb and designed and made a new board. This board syncronizes the flashing light with the sound. So I have an rca connector on the case of the strobe light that connects to the audio that also feeds my amplifier. The sound reminds me of going to bed at night on a wooden minesweeper that used diesel power. The low sound of the diesel would put me to sleep every time.

  • Riley Casey

    Some related mechanics to all this. 40 Hz is a physically long wavelength, the full wave is 28 feet long. While this doesn’t mean you need to be in a large room to hear it it does mean that much of the bodies ‘awareness’ of the sound is distributed across more than just the ears. Headphones, ear buds and computer speakers will not produce the fundamental 40 hz tone but are more likely to produce overtones created by those small devices distorting the sound. The low E note of a bass guitar is 41 hz for reference. Anyone with smart phone can download a signal generator app that will produce a pure 40 hz sine wave. The trick will be to reproduce that with an amplifier and speaker capable of true low frequency reproduction. Even at low volumes you will need a speaker with an 8″ woofer at a minimum. Subwoofers are specifically designed to reproduce these low tones. Most low budget home music systems will likely produce annoying distortion when trying to reproduce a 40 hz signal and that distortion may well create results opposite that you hope to achieve.

    • wolf

      my $39 20hz-20khz headphones reproduce it super cleanly no issue and the sternum does respond aka the bones do vibrate regardless.

  • Elda

    I get completely insane from 46 – 52 hz wobble. I would stand up from my grave to make it stop. Don’t experiment with people with those tones. Play nice tones instead, calming nature sounds or music from their youth. Be careful!

  • Alexander

    Here are my personal experiences with a 40hz tone.
    At the beginning when I found this web site I used to listen to the tone on my headphones but after a while, I was thinking to switch to a big subwoofer in order my brain pickup that vibration. So I put earplugs to protect my hearing and turn on 40hz tone and set to loud.
    I use to lay down on a yoga matt near the speaker and relax for 10 minutes. Usually, you can feel the vibrations all around your head, for me, it’s a pleasant experience.
    I don’t know is this good approach but after this I feel mental clarity.

    Does anyone of you guys tried this?

  • Walt

    I’m listening to the the 40 Hz on my iMac with a set of plug-in ear buds that used to come with Apple products. It feels like my whole body and the things I am touching (the chair and the wood floor) are all vibrating together.

  • Penny

    I am 72 years old and I have fibromyalgia. I was interested in trying this tone generator at 40 hz for the prevention of Alzheimer’s Disease. I turn the sound on every morning at the sine wave setting and leave it on all day. I also have a 40 hz light that I aim at my face when I’m on the computer, which I got online through Amazon. I have no trouble hearing the sound – these are good speakers – but I also feel it, as well. It feels like a rumbling of thunder in my chest. It’s not bothersome and in fact is rather soothing. My husband likes the sound to be on, but he can’t do it when he’s meditating, he says it interferes with the waves he’s trying to generate when in meditation.

    I don’t have Alzheimer’s Disease, but I have noticed my brain works better. In the lore of fibromyalgia, we have this thing we call “fibro fog” which makes it hard to concentrate sometimes. The combination of the light and sound have helped my foggy brain. Maybe it will keep me from getting Alzheimer’s.

    It has done nothing for my fibro pain. I use cannabis for that. It takes a very long time to find which strain helps you the most, but when you find it, you will not regret it.

  • Gerhard Umlandt

    The scientific basics on which all this works is the
    so called “frequency followig response” effect of
    the brain. The brain tries to adapt to a given external
    frequency. Since 40 Hz is equivalent of being “awake”
    and “intelligent thinking”, one can induce this status
    into the brain from outside, at least to a certain extent.

    This leads to the question, how to applicate this 40 Hz?

    A 40 Hz sine wave is a very deep tone. Your laptop speakers
    cannot reproduce this at all! And your loudspeaker in your
    bookshelf cannot do this either! You would need expensive
    professional loudspeakers, if you want to perform a pure
    40 Hz sine wave sound.

    But fortunately, this is not necessary. Why? What´s our aim?
    Influencing the brain. But the nerve cells of the brain don´t
    produce sine waves. In the 70s I was involved in detecting
    and amplificating nerve signals. Nerve cells do not generate
    sine waves, but short pulses (in German: “evozierte Potentiale”;
    evoced electrical signals). The sound is like clicking or
    crackling. It´s short pulses. So there´s no need for a
    40 Hz foundamental sine wave, but harmonic waves with
    higher frequencies and a repetition rate of 40 Hz will do and
    are appropriate! And this can be achieved easily.

    The easiest way is to switch from wave form “sine” to
    “sawtooth” in the online sound generator. So you will
    get 40 pulses per second, that are audible very well
    (with small speakers, too).

    The waveform of sawtooth is a linear ramp – correspondig
    to the deep frequencies – and a vertical pulse – corresponding
    to the harmonics, the higher frequencies.
    That´s what we need!

    If you applicate the sound via an external amplifier and
    loudspeakers, you can control the sound much more.
    In this case, turn on the treble control and turn down
    the base control completely.

    If you are an electronics technician or radio amateur,
    you can build a little sound generator circuit, that
    produces needle pulses or sawtooth wave form with
    following differenciation (for there´s no reason occupying
    a laptop or pc with such a simple task). When using a
    sawtooth generator add a further so called RC-derivative
    element, what is simply a condensor and a resistor, that
    allows to pass through higher frequencies, only, so that
    the result in sound is equivalent to the needle pulse generator.

    Compare the right 40 Hz frequency with the online
    frequency generator using the sawtooth wave form.

    You need not have any fear! Nobody will die, if you use
    41 instead of 40 Hertz! 🙂

  • Gerhard Umlandt

    A further possibility would be, to applicate a 40 Hz signal
    directly via electrodes, that are attached to the skull, to the
    brain. But this is for experts, only. Maybe you know the
    “alpha-stim” (ulator). But this requires knowledge of the
    right amplitudes, finally we won´t give the brain an electro shock.
    In this case no connection to the mains is allowed, only
    battery supply!

  • Jon Ahlquist

    If people Google”40Hz Alzheimer’s”, you can find a number of studies that are not behind a paywall, such as:

    For people at universities who have access to the “Web of Science” search engine, a search on 26 September 2020 for “40HZ Alzheimer’s” found 74 articles published in research journals.

  • Rob

    I am looking for some kind of 40 Hz lighting device to add to the 40 Hz. accoustic and vibration stimulation. Just wondering whether anyone here has had any experience with the AlzLife app (it uses 40 Hz flickering light and sound coupled with mental stimulation in the form of games). Has anyone had any experience with this app? Also: I have heard that the frequency of 40 Hz in a tablet is not be same as that if a 40 Hz LED light. Can anyone tell me whether this is correct. Many thanks! Rob

    • Tomasz P. Szynalski

      Tablets typically have screens that refresh at 60 Hz or 120 Hz (iPad Pro). 60 Hz screens cannot display 40 Hz flicker the way it was done in the MIT mouse experiment (light changing its state 80 times a second). 120 Hz screens will sort of do it, but not accurately. 160 Hz would be ideal. I’d expect better results with variable refresh rate screens, such as computer gaming displays with adaptive sync.

  • Gregory Whitchurch

    I’ve been out-of-touch here for a while now, sorry. Very glad to see folks chiming in, & to see the ongoing research in this area. (Some promising Alzheimer’s tests in development now!)

    I previously reported anecdotal, subjective outcomes for my late-90s Mom. She passed away 1.5 yrs. ago now. But my Dad, Wife & I all believed her memory loss & concentration improved noticeably, altho not very far, after the “therapy” I hereinbefore described.
    I’ve since shared a couple of links on this subject.

    Now I’m writing to catch up. My Dad had essential tremors (head & hands) going back into the aughts. a few years ago he lost the ability to trim my Mom’s & his finger nails – so I chipped in.
    We have continued the “therapy” for him. Six mos. or so ago we were able to conclude (as did his drs.) that those tremors are no longer evident. He trims his own nails again, & his head & hands are steady.
    We run 40Hz. sine or saw-tooth sounds at low volume (meaning it doesn’t bother any of the 3 of us – altho my Wife is the one who complained when it was too loud).
    My solution for my Wife & my living area is sawtooth on laptops – Dad has the subwoofer. But we rarely do it, so far. We’re in our early 70s & can’t remember if our memories are fading or not! ;-))

    • sharon

      what are the specifics for your Dad? i.e. how long are the sessions? how many times per day? how many times per week?

      remarkable after 6 months you saw a significant reduction in his tremors. how old is your dad? does he still follow your “therapy’?


  • Russ Heron

    Tomasz, I have never commented on a website before but after reading this post about your tone generator I wanted to reach out to you. I have been making sun visors with bright white LED’s flickering at 40hz directly into the eyes for various family and friends dealing with alzheimer’s, dementia and in one case cognitive issues from a stroke. None of this is proper science, but more like anecdotal evidence. All but one of 2 dozen I have made have seen improvement. I am not in this as a business but if you email me I will happily supply you with information on how to make the same device.

    • Tomasz P. Szynalski

      Why don’t you publish the information on the Web? I’ll be happy to link to it.

    • Rob

      Hi Russ. That is fantastic. It would be great if you could share how you made these. I am especially interested in the type of light used and the intensity (there are 40 hz gamma lights on the market, but they all advise to keep the light in your peripheral vision. However, the lights used in the research with human subjects are shined directly into the subject’s eyes. Any information you could provide would be greatly appreciated. Additionally….if you were to consider a business making these, I would be an interested customer. Thanks.

      • Russ

        I don’t have a website to publish any info and I’m not on any type of social media, but I will try to describe it here. I start with a cheap dark colored sun visor. I use a battery pack for 2 2032 coin cell batteries that is slightly larger than a U.S. quarter in diameter and power an arduino board, a Gemma M0 that is also comparable to a quarter, and both are mounted to the top of the visor. The board is fully programmable and to get a 40 hz output you turn on 2 led’s for 12.5 ms and off for 12.5 ms. The M0 board can’t quite do that so I use on for 12ms and off for 13ms. 2 led’s are mounted under the visor aimed directly at the eyes at a 45 degree angle. The led’s are mounted so the light will shine over a pair of glasses. The result is a 40 hz bright white light shining directly into the eyes that does not interfere with performing regular tasks. I tested it by reading a book and watching a movie on my phone. An audio component could be added but it significantly raises the discomfort level of wearing it and it would increase the cost. As is, the device can be made for less than $50 with off the shelf components.

    • SoonLye

      Hello, Can you please send me the relevant information to make the 40Hz glasses ..e.g circuit, software, parts, how to use etc. Thanks in advance.

  • Juliet

    Thank you all for the information. I am not good at electrical and soldering work. Any pictures available and hints as to how to connect it all up. Otherwise, can I buy Russ’s device or any other devices mentioned?

    • SoonLye

      Hello Juliet, My name is Soon Lye. Whereabouts are you in Australia ? I live in Melbourne, Vic and depending on where you live and the complexity of the device that Russ has designed – I would be happy to help you build it. I am a volunteer helping folks with disabilities . My current volunteer research interest is in Orthostatic and Essential Tremor. Regards.

      • Dan Damon


        I have built a device for my father that includes a 40Hz plug to drive LED christmas tree lights as well as a synchronized 40 Hz tone output. The circuit includes fairly common parts, probably around 25 dollars worth.

        If your power is 110 volts, should work for you. I’ll be glad to share the circuit diagram and component list if you’d like. Sounds like you are doing good work.


  • Tim

    Here is a track on youtube which I believe matches the 40 hz clicks in the MIT

  • Rob

    Can anyone recommend a subwoofer ( Bluetooth preferably) which would be sufficient to use for 40 Hz? Is there a reasonably-priced one on the market? Many thanks.

    • Paul Gallagher

      I checked out bluetooth speakers on Ebay. I found out that speaker wattage has to be around 12watts or more, to be able to obtain the correct volume level. I also discovered the best way of delivering the 40Hz Frequency to the body is to lie down with the speaker underneath an inflatable travel cushion, or, some bubble wrap.

  • Emily Salmon

    Thanks for this! Radiolab has an update episode called “Bringing Gamma Back, Again”.

    The logic behind binaural beats makes sense to me- I’m a professional violinist and when unison tones are out of tune there are “beats” that I understand to be the frequency of the discrepancy in the intonation. I’m curious if this phenomenon is actually a viable solution to the “clicks vs true tone” question.

    Functional bad intonation

  • Kim

    Any new encouraging research?

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