What does 40 Hz do to the brain?

A steady 40 Hz rhythm can make groups of brain cells fire in step at that rate, which researchers call entrainment. A 2020 brain scanning study confirmed this happens with 40 Hz binaural beats. What that does for thinking in daily life is still being studied.

Do 40 Hz binaural beats improve focus?

Possibly, a little. One small 2020 study found people learned an attention task faster with 40 Hz beats, but the gain showed up the next day, not while listening. Treat it as something to test for yourself.

Is 40 Hz gamma good for memory?

In mice bred to model Alzheimer’s, a week of 40 Hz sound improved memory tests. That has not been shown in people, and 40 Hz sound is not a treatment for memory loss or dementia.

When should I listen to 40 Hz?

During tasks that need alert attention, such as studying or detailed work, for 10 to 20 minutes. Avoid it before bed: gamma is a waking rhythm, and slower bands suit sleep.

Is it safe to listen to 40 Hz sound?

For most people, yes, at a low volume. If you have epilepsy or a seizure disorder, ask your doctor first, and never listen to brainwave audio while driving.

40 Hz Binaural Beats: Gamma Waves and the Research

40 Hz binaural beats target gamma waves (about 30 to 100 Hz). Mouse studies on Alzheimer’s are promising, but evidence for focus in people is small and early.

What are 40 Hz binaural beats?

40 Hz binaural beats are two tones, one in each ear, that differ by 40 Hz, so your brain hears a rhythm pulsing 40 times a second. A tone of 200 Hz in the left ear and 240 Hz in the right gives a 40 Hz beat. If the idea is new, start with what binaural beats are.

That rate sits in the gamma band. Brainwaves are the electrical rhythms your brain cells make when they fire together, and they are grouped by speed:

Band	Range	Often linked with
Delta	0.5 to 4 Hz	Deep sleep
Theta	4 to 8 Hz	Drowsiness, meditation
Alpha	8 to 12 Hz	Relaxed, awake
Beta	12 to 30 Hz	Active thinking
Gamma	30 to 100 Hz	Attention, memory, binding information together

40 Hz gets special attention because it is a rhythm the brain produces strongly on its own, and because of a run of studies from MIT.

What did the MIT 40 Hz research find?

In mice, 40 Hz light and sound reduced the build up of amyloid beta, the sticky protein that forms plaques in Alzheimer’s disease. In a 2016 study in Nature, light flickering 40 times a second lowered amyloid in the visual part of the brain and reduced plaques in older mice. Other flicker rates did not have the same effect.

A 2019 follow up in Cell used sound: clicks played 40 times a second, one hour a day for seven days. The mice did better on memory tests and had less amyloid in the hearing and memory areas of the brain. Sound and light together reached more of the brain than either alone.

Two points matter here. First, these were mice bred to develop Alzheimer’s type changes, not people. Second, the sound was a train of clicks from a speaker, not a binaural beat.

Does 40 Hz work in humans?

It is not proven. Human studies of 40 Hz light and sound are still early and small. No result so far shows that 40 Hz sound prevents, slows or treats Alzheimer’s in people.

The mouse findings are also debated. A 2023 study in Nature Neuroscience tested 40 Hz flickering light in two mouse models and found it did not drive gamma rhythms deep in the brain and did not reduce amyloid. Science often moves like this: a striking result, then careful checks. Until larger human trials report clear results, the honest answer is “interesting, not established”.

Can 40 Hz binaural beats help you focus?

There is some early evidence. A 2020 study in Scientific Reports recorded brain activity while people listened to 40 Hz binaural beats and confirmed strong gamma activity in step with the beat. Over three days of training on a fast attention task, people improved more after their 40 Hz day than after a 16 Hz day.

The gain did not appear while they were listening. It showed up the next day, after sleep, which suggests the beat helped learning settle rather than giving an instant boost. It was a single, small study. For a wider look at sound and attention, see binaural beats for focus and the bigger question of whether binaural beats work at all.

How should you try 40 Hz?

Keep it short, quiet and tied to a task. A simple way to start:

Length: 10 to 20 minutes, during work that needs alert attention.
Volume: low. The tones only need to be just audible.
Headphones: needed for binaural beats, since each ear must get its own tone.
Timing: earlier in the day. Gamma is a waking rhythm, so skip it in the hour before sleep.

At 40 Hz, a binaural beat feels faint, more like a slight roughness than a clear pulse. If you want a crisper rhythm, or want to listen through a speaker, isochronic tones switch a single tone on and off 40 times a second. That is closer to the click trains used in the mouse research. Shimmr can play Gamma either way, generated live on your iPhone: Deep Focus in the library holds a binaural 40 Hz beat, and the isochronic sessions run from Delta to Gamma.

Is 40 Hz sound safe?

For most people, listening to 40 Hz tones at a low volume carries little risk. The bigger risks are loud volume over long periods and listening when you need full attention elsewhere. Never listen to brainwave audio while driving.

If you have epilepsy or have had a seizure, talk to your doctor before using rhythmic sound, and stop if you feel unwell. If you are worried about your memory, or someone close to you, see a doctor. A sound session is not a substitute for a medical check.

This article is for general information and is not medical advice. Binaural beats are not a treatment for insomnia or any other condition.

40 Hz binaural beats and gamma waves: what the research says