Technology Serving Consciousness

The Brain’s Frequencies

Brain Electrical Spectrum

The marvels of human Experience and our states of consciousness can be measured, and so objectified by using the electroencephalograph (EEG)! Though incredibly complex, the human brain follows norms of activity that repeat throughout the entire organ. The electroencephalograph is able to read the electrical potentials that are liberated by the neurons (brain cells) while they send their electrical messages across the body of the cell. When a great number of neurons liberate electricity at the same frequency (speed) in a localized area, they generate an electrical potential sufficiently large to be read by the sensor which is placed on the scalp over that area.

The number of neurons using a certain frequency to pass their messages is what defines the amplitude (power) of what the EEG reads. When we look at a spectrum of all the frequencies that are read by the EEG, we can usually notice one frequency that has an amplitude which predominates over the other frequencies. Here we see the electrical speed that is guiding the consciousness of that person at that instant (highly simplified).

This short text will serve to demonstrate the seven frequencies that are most recognized as "states of consciousness." Our understanding of the link between a brain frequency and a perceptual state comes to us with a LOT of research supporting it. Since 1929, neurologists, psychiatrists, anatomists, electrical engineers, and millions of research subjects have worked together to create a basic understanding of "consciousness." Today this knowledge is already applied on the clinical level; with consistently replicable results. Thus it is worth the effort to learn and remember this little bit of basic theory before going further into study of different problematic brain-electrical patterns. This "map" of consciousness can help you decide where you want to guide yourself.

Frequencies are measured in Hertz (waves per second). Manually reading the raw wave-form information is simple, though slow. The computer is able to instantly translate the waves into more palpable forms. This doesn’t free us professionals from the responsibility to, at least, be able to do a manual reading of the raw information which we receive. Let’s look from slowest to fastest.

Delta: 0-4 Hz


Note that each vertical line of this wave-form represents one second. Now, choosing the second second, count how many times the wave has passed through the midline. Each two times that a wave passes through the mid-line equal one wave. In the second "epoch" (in this case, an "epoch" is one second long) we can count 4 waves, and so we have defined this epoch as predominantly Delta.

Delta predominates in the brain when a person is in profound sleep, with the consciousness completely internalized. For the body's cells, Delta serves as a regenerative state. If a person has a predominance of Delta while awake, he will have difficulties even telling us that he is very tired. This person will have a manner that appears disconnected from his surrounding society.

In biofeedback, it is extremely rare to train an increase in Delta (only for experiences with transcendental states). And it is also rare to train to reduce Delta. Instead, trainers can choose to train to reduce the activity of ALL the frequencies, including Delta.

Theta: 4-8Hz


The Theta waveform looks very much like the Delta wave. Both have a sort of flat spot on their peak, both are large and wide. The difference we see here is that we can count 4 to 8 waves inside any one second of Theta. The image at left shows that the epoch has amplitudes predominating at 6Hz, though it is easy to see that this image also has some Delta waves and also some Alpha. Remember that it is the wave that exerts the greatest amplitude that is considered "Head"of that brain region at that time.

When Theta is "Head" of the consciousness, the person could be considered sleeping while awake, in trance, intuitive and internal. This person will have difficulty maintaining a conversation and looking in the other’s eyes at the same time, because the connection with another breaks that "center of the universal" feeling. Theta is a creative state that doesn’t keep a single point of focus. Thoughts in Theta are visual/emotional as opposed to linguistic/rational thought.

When a person generates only Theta it is generally because of a lack of oxygen and also blood flow. With low levels of that life-giving liquid, the brain is forced to operate at slow speeds of function. These people can have problems with the pace of our society. They have difficulty maintaining one job because of the inadequacies Theta has maintaining external attention. They certainly will have difficulties in situations like a classroom or a rigidly structured job-place.

However, it is important to look at the whole spectrum before deciding what is someone’s state of consciousness. For example, if a person generates a lot of Theta and at the same time relatively high levels of Beta or Alpha, the two speeds will be in balance with each other, and the person’s personality will not necessarily be internal, perhaps a bit more "colorful".

Alpha: 8-12Hz


This wave has now sharpened itself. The Alpha waveform doesn’t have those flat tops and wide troughs. It is a smooth and thin wave which oscillates from 8 to 12 times in a second. In the second, third, and fourth second of this image almost all the waves are at the Alpha frequency (minus an eye-blink and a couple of dips into Theta).

Alpha is the moment that a person has looked out from inside solely his or herself and looked to the world about. It is still not a very active state of consciousness. It is merely observing the surroundings. It’s in this state that we sense the beauty of the sea and we sing along to our favorite song. It is in Alpha that a person is able to listen during a conversation, without thinking of his or her own response. Simply listening.

When it is the all-time predominant frequency being generated, this person will have problems acting on ideas. He or she can have excellent ideas, but lack motivation. On the contrary, if a person is hardly able to generate Alpha (especially if the person strongly generates Beta at the same time) he or she can have problems with fatigue and anxiety which build up to more destructive diseases bred through the stress of constant vigilance.The person will lost contact with the silence that recharges our patience and our mind so that we may be productive and in contact with our surroundings.

SMR: 12-16 Hz


Looking at these waves, you may appreciate how it is a slow and laborious process to count waves manually. By the bar-graph at the left, the tallest bar appears to be at the high end of SMR (which stands for SensoriMotor Rhythm) at 15 Hertz. This frequency is generated almost exclusively by the SensoriMotor Strip- a band on the cortex which runs almost from ear to ear (temporal lobe to temporal lobe).

The sensations of this brain frequency are similar to those of Alpha, but more in the body- our awareness of our bodies within the present environment- and most importantly, it is the speed at which we begin interacting with our environment. This trait brings some researchers to include SMR as a sub-state within Beta.

He or she who generates high levels of SMR is the basketball star or the talented dancer. A practiced dancer does not need to think anymore about how he or she will perform the choreography. Having already practiced (Beta) they simply let their bodies do the movements as if in autopilot.

When a person doesn’t generate much of this frequency, that person will have problems with sensations of the body (more intensely felt pains, less control of bodily functions). This person will have less dexterity and will also be more impulsive in speech and actions. A clear indicator of low SMR is the inability to fall asleep without being physically exhausted. This frequency is a key rhythm for the well-being of the body and also the mind.

Beta: 16-20Hz


Beta is an athletic state of consciousness. The brain, to maintain such an elevated rhythm (remember that "Hertz" means waves per second) will have to have the resources of healthy oxygen and glucose levels in the blood. Even with these conditions met, to maintain the Beta state, the neurons will enter into polyrhythms. In other words, instead of all the neurons sending their charge simultaneously, various smaller groups set off chains or currents, without having to maintain one central pulse throughout the cortex.

The EEG sensor reads this as a lot of waves per second at a lower amplitude. Notice this on the bar graph at left in the way that the bar is not very tall, but is widely dispersed.

In Beta, we are able to push around the thousand details which join to build one project. We are able to plan our week in advance. We study and learn in Beta. Whatever requires pre-planning and language or numbers will make use of the forces of Beta.

When Beta predominates and is not balanced by the presence of Alpha in the spectrum, the sensation is displeasing. It is when a person is thinking and is not able to stop thinking. These thoughts close in on themselves and appear not to have a way out of the thinking and planning and worrying. In other words, anxiety. The state of depression also has this brain-wave pattern (with some distinct nuances).

When a person cannot sustain the Beta speed, he or she will have difficulties with reading and planning. This is usually negatively enhanced by the presence of higher levels of Theta, which serve to create an even more diffuse state.

Beta2: 20-24Hz


This is the speed of Beta which the reader is probably using to cogitate the information in this text. In that this text concerns itself with abstract concepts such as Frequency and Amplitude, State of Consciousness and Awareness. It is challenging the brain to create a framework within which this information can be processed. The faster speeds of the brain seem to be able to perform functions somewhat like the slower speeds, though in a different manner.

The information has been broken down to such a minute piece that the pieces may be re constructed in different forms. There is a certain creative license within abstract thought. Though, unlike the abstract intuitive thought of the Theta speeds, this type has "Whys" and "Wherefores" to support its LOGIC.

This is very rarely the predominant brain frequency. It can be seen to rise when a person performs math tasks, or some other such cognitive challenge in his or her head. Again, when measuring the state of consciousness with regards to these faster frequencies (The Beta Waves), we look not only at the amplitude of those frequencies, but how powerful they are in comparison to other frequencies within the range.

Beta2 is not a frequency that is commonly used, neither to increase nor to reduce in the Neurofeedback paradigm.

Beta3: 24-38Hz


By this speed, there may already be a sensation felt bodily. It is a highly motivating frequency for its electricity is felt as a certain discomfort. When continuous and untempered by Alpha, it can be experienced as the racing mind that cannot be quieted. It is the mindset that motivates its owner into action. It is a thought that has followed its own tail and the person cannot find the way out. Stressful experiences will generate this frequency. The feeling of wanting to be out of a situation and the discomfort of not being able to free oneself of that situation can be seen as increases of the Beta3 frequency.

Also noted experientially is the auto censoring which can occur inside the mind of an anxious person. Sometimes the person is guarding his or her psyche from painful memories. Sometimes it increases due to social training. It is the vigilance that notices banished thoughts or emotions arising and blocks them from surfacing to the lower Betas.

These very fast speeds of the brain approach the slow speeds of the human muscles. So when making EEG readings above 28Hz. the psycho-physiologist must be careful to account for muscle tension. However, there is a link between increased facial muscle tension and increased psychological stress.

So there will also be a link between decreased muscle tension and decreased Beta3. In a biofeedback protocol, this is a commonly seen feedback frequency. Most any training protocol for the increase of attention and self control, as well as for the increase of calm will screen for the Beta3 frequencies and reward their reduction.


We see that each brain frequency has important uses in our every day, and that if any one frequency becomes fixed as the "main" wave we have difficulties doing the tasks that the predominating wave is not effective with. It appears that the state of mental (and, through association, physical) health is not the presence of any one wave, but the equal relationship between the different waves and the ability to change predominance to face the changing demands of our environment.