Brainwave Entrainment: A Technology to Improve Focus, Reduce Anxiety, and Enhance Meditation

Mats
7 min readJun 8, 2023

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Image by vecstock on Freepik.

If you are a psychonaut or someone who has scoured the internet for brain-hacks and alternative treatments, you may have come across brainwave entrainment (BWE).

Brainwave entrainment is located somewhere in between the areas of neuroscience and self-improvement. Many potential uses for the technology have been discovered, from inducing altered states of consciousness to treating migraines. It might be efficacious in depression, anxiety, ADHD, and learning disorders. It is also said to strengthen and deepen your meditation. Despite its numerous uses, few have heard of brainwave entrainment.

So what is BWE? To answer this, we must first look at brain waves themselves.

What are brainwaves?

Brainwaves are patterns of electrical activity in the brain, measured on an EEG by attaching sensors to the head. The waves are neuronal activity caused by patterns of synchronized electrical pulses, measured in cycles per second (Hz).

We can divide frequencies of brainwaves into bands, based on the observable effect those frequencies have on the brain and the person’s subjective experience.

We name the frequency bands commonly recognized as follows: Delta, Theta, Alpha, Mu, SMR, Beta, and Gamma. These are all associated with different activity in the brain, different effects on behavior, and changes in cognition.

The different brainwave bands

Let’s take a closer look at each of the brainwave frequency bands.

Delta Waves (0.5–4 Hz):

  • Delta brainwaves are linked to dreamless sleep and deep meditative states. Due to its connection with deep sleep, it’s associated with healing and restoration.
  • Presence of Delta waves during waking could indicate abnormalities, such as dementia or Alzheimer’s disease.
  • Disruption in Delta wave production during sleep is associated with ADHD, increased risk of diabetes, schizophrenia, anxiety, OCD, and Parkinson’s disease.

Theta Waves (4–8 Hz):

  • Theta brain waves occur during REM sleep and are also found in deep meditation. Sleepiness increases as theta wave activity increases.
  • Linked to memory formation and involved in moving meaningful events into long-term memory.
  • Hypnosis can produce Theta waves to provide anxiety relief, which can help process traumatic memories.
  • Too much Theta activity during the waking state is abnormal; it’s seen in ADHD, learning disabilities, and head injuries.

Alpha Waves (8–12 Hz):

  • Alpha brainwaves are associated with daydreaming — a resting state without strong external focus. They are the most prominent brain waves during relaxed awareness.
  • Meditation increases alpha wave presence.
  • Average Alpha frequency may slow due to ageing, dementia, Alzheimer’s, or head injury. Low average Alpha presence is linked with a decline in cognitive abilities.

Mu Waves (7.5–12.5 Hz):

  • A sub-band of Alpha waves. Similar to Alpha and related to motor system activation.
  • Mu brain waves occur in the motor cortex, the part of the brain that controls voluntary movement. Mu rhythm is suppressed when performing movement. With practice, it’s also possible to suppress Mu waves when visualizing performing movements.
  • Mu waves can be used to create a brain-computer interface (BCI) to help those physically disabled.

Beta Waves (12.5–30 Hz):

  • Beta brain waves dominate our everyday state. They are associated with focus directed externally.
  • Too much Beta can cause states of excessive mental arousal — anxiety, OCD, hyperactivity, sleep problems, and so on.
  • Too little Beta is a sign of under arousal and associated with problems in concentration and problem-solving.

Sensorimotor rhythm (SMR) (13–15 Hz):

  • A sub-band of Beta waves.
  • Sensorimotor rhythm, as the name indicates, appears in the sensorimotor cortex of the brain.
  • SMR increases in strength when a person is physically idle, and decreases in strength when motor activity increases. Even imagining physical movement causes SMR amplitude to weaken.

Gamma Waves (25–140 Hz):

  • Gamma rhythms relate to large-scale brain network activity. It’s connected with functions like working memory, attention, and perceptual grouping.
  • Typically, 40 Hz is the frequency of interest in this band.
  • Irregularities in Gamma waves are associated with ADHD and learning disabilities. It can cause difficulty with concentration, attention span, working memory, and other cognitive abilities.
  • Gamma waves may play a part in creating unified perceptions of the world, because of its apparent role in synchronizing neural activity across separate parts of the brain.
  • The amplitude of Gamma increases with skill in meditation.

What is Brainwave Entrainment?

This brings us to BWE, which is an attempt to induce the various brainwave frequency bands at will. The hope is that this will have a beneficial and therapeutic effect. Researchers and clinicians have tested it as a treatment for a variety of neurological and physiological problems, as mentioned previously.

The phenomenon used to achieve this is known as entrainment, which is the phenomenon where two oscillating systems assume the same frequency by interacting. BWE exploits the frequency following effect of the brain, making it switch to a state matching the frequency it’s being exposed to. Sound, light, and electromagnetic field can all be used to create a frequency following response. This is similar to tribal or shamanistic practices involving rhythmic drumming and flickering fires that attempt to induce altered states.

BWE is more simply explained as neural activity being synced to external stimulation.

A BWE session will typically last a minimum of 10 minutes, as it takes some time for the brainwaves to become entrained to the input stimulation. Adding light stimulation reduces the time needed to achieve entrainment. The session should be repeated over a period of time so that the brain learns to reproduce the desired brain state one its own.

Types of Brainwave Entrainment

There are various methods of creating entrainment through sound: binaural beats, monaural beats, and isochronic tones. We can use any of these in combination with visual stimulation. The most common forms of BWE are binaural beats and isochronic tones.

Binaural beats

In binaural beats, two different signals, one in each ear, combine in the brain. By sending two signals that are close in frequency separately into each ear, through stereo headphones or speakers, the brain produces a third, phantom signal. The phantom signal represents the difference in frequency between the two signals.

For example, if one signal is 120 Hz and the other is 100 Hz, the brain will perceive 20 Hz as the frequency of the signal. Brainwave entrainment will then occur at that frequency, which corresponds to Beta waves.

How binaural beats are perceived by the brain. [Source]

Isochronic tones

For isochronic tones, one beat of one tone regularly repeats. This is done by rapidly switching the tone on and off. The number of beats per second is the frequency of the tone. Isochronic tones create a more powerful entrainment effect than binaural or monaural beats. This is due to creating a more obvious beat for the brain to entrain to, as seen in the image below.

How isochronic tones are perceived by the brain. [Source]

Monaural beats

Monaural derives from the word mono, meaning “single” or “one”. Like binaural beats, it creates a single beat by combining two distinct tones. Unlike the binaural method, it mixes the two tones into a single beat, in a single speaker, before the tone reaches the ears.

Monaural beats are as effective as binaural beats, but are less pleasant to listen to, and more difficult to combine with other sounds (music or white-noise).

How monaural beats are perceived by the brain. [Source]

What is Audio-Visual Entrainment?

Audio-Visual Entrainment (AVE) is brainwave entrainment performed using a combination of visual and auditory input, where a flashing light synchronizes with a rhythmic beat. As mentioned earlier, this is more effective in establishing entrainment than sound alone.

Light stimulation is delivered by glasses with LEDs attached on the inside, or through a lamp or screen. If using a lamp or screen, the eyes may be kept open. With glasses, they’re typically kept closed. Those who are photosensitive must be careful using AVE, as the flashing lights might trigger a seizure.

Image of the Proteus brand mind-machine. [Source]

A computer or device decodes a file that contains information on how the auditory & visual input should synchronize. We often refer to a device that does the synchronization as a light & sound machine, mind machine or, less frequently, brain machine.

We can also use biofeedback and neurofeedback alongside AVE. The readings from the feedback devices can be used to change the entrainment session on the fly. The idea being to guide the brain to the desired entrainment state more effectively by tailoring the session to the individual user.

Conclusion

As we have seen, brainwave entrainment exploits the natural phenomenon of entrainment to create various mental states. It has the potential to assist with a variety of problems and aims.

Different kinds of auditory entrainment, visual stimulation, biofeedback, and neurofeedback can be used for greater effectiveness. Visual stimulation creates stronger & faster entrainment, and bio- & neuro-feedback allows the entrainment sessions to be personally tailored.

The technology have long been known in more “alternative” circles, and is known in some clinical and research areas, but the mainstream have rarely heard of it. The potential of the technology justifies it being better known.

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Mats
Mats

Written by Mats

I'm an engineer by trade and a writer at heart. This is where I write about everything I learn on my journey to a better life.

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