40 Hz gamma sound
The 40 Hz pulse from the Alzheimer’s research, and the 40 Hz binaural beat, free in your browser. Plus what the studies did and didn’t show.
The pulse works on any speaker. The binaural version needs headphones. Keep it short and soft: a fast pulse gets tiring.
A 25-minute session of 40 Hz clicks in the style the studies used, with visuals.
Why 40 Hz
Studies40 Hz sits in the gamma band of brain waves. In 2016 an MIT team led by Li-Huei Tsai found that light flickering 40 times a second lowered amyloid, a protein linked to Alzheimer’s disease, in the brains of mice[1]. In 2019 they added sound: 40 Hz clicks alone reduced amyloid in the hearing and memory areas of Alzheimer’s-model mice and improved their memory, and clicks plus light reduced it across more of the brain[2].
In people
StudiesSmall human studies have followed. A 2022 pilot randomly assigned 15 people with mild Alzheimer’s dementia to an hour a day at home of either 40 Hz light and sound or a placebo version (steady light and white noise). The 40 Hz device was well tolerated; the results on memory and brain scans were exploratory and need a larger trial[3]. A larger trial of about 670 people finished enrolling in 2025, and its results haven’t been published yet[4]. Nothing so far shows that listening at home treats, prevents or slows anything.
Pulse vs binaural beat
MeasuredThe studies used sound that really pulses 40 times a second: clicks, or a tone switching on and off. You can hear that on any speaker. A 40 Hz binaural beat is a different thing: two steady tones 40 Hz apart, one in each ear, so the beat exists only inside your head. They aren’t interchangeable, and only the pulse matches what the studies used. The pulse on this page is a 200 Hz tone whose loudness rises and falls 40 times a second; the Lab’s 40 Hz Clicks session uses sharp clicks like the mouse studies.
If you have epilepsy, ask your doctor before using pulsing sounds.
Focus Builder: five work blocks
One work block a day, each with a different kind of sound. Day 4 is the 40 Hz click session. Day 1 is free.
Questions
Does 40 Hz sound help focus?
Some people use it for focus and like it. The research above is about Alzheimer’s pathology in mice and early safety in people, not focus. Treat it like any work sound: use it if it helps.
Is a 40 Hz binaural beat the same as the MIT sound?
No. The MIT studies used real 40 Hz clicks you can hear on a speaker. A binaural beat makes a 40 Hz difference between the ears instead. Use the pulse if you want to match the studies.
Can I hear 40 Hz on its own?
A pure 40 Hz tone is a very low hum that most phone and laptop speakers can’t play. That’s why 40 Hz sounds are made from a higher tone that pulses 40 times a second.
Sources
- Iaccarino HF, Singer AC, Martorell AJ, et al. Gamma frequency entrainment attenuates amyloid load and modifies microglia. Nature 540:230–235 (2016). doi:10.1038/nature20587
- Martorell AJ, Paulson AL, Suk HJ, et al. Multi-sensory gamma stimulation ameliorates Alzheimer’s-associated pathology and improves cognition. Cell 177(2):256–271 (2019). doi:10.1016/j.cell.2019.02.014
- Chan D, Suk HJ, Jackson BL, et al. Gamma frequency sensory stimulation in mild probable Alzheimer’s dementia patients: results of feasibility and pilot studies. PLOS ONE 17(12):e0278412 (2022). doi:10.1371/journal.pone.0278412
- ClinicalTrials.gov NCT05637801: the HOPE study of 40 Hz sensory stimulation in Alzheimer’s disease. clinicaltrials.gov/study/NCT05637801