What is the function of the various brainwaves?

A man named Caton first discovered electrical rhythms within the brains of animals in 1875. It was over 50 years later when Hans Berger showed that man also had these rhythms. His original search was in the hopes of finding the physical link between man's mind and his body.
It was this mind/body question which led him to dedicate his life to finding this link. He became interested in the work of Caton and others and set up his own laboratory to further investigate the electrical activity of the brain.

After 20 years of research, he was first able to record the brain rhythms of a human. He spent another 10 years convincing his colleagues that this rhythm came from the neurons of the brain, not from blood flow or connective tissue.

nimation courtesy of Dr. Dan Russell, Kettering University

His original studies also showed that this rhythm changed with age, was vulnerable to sensory stimulation, and was affected by body chemistry.
World War II broke out and Hans Berger never finished his original work: crack the code of brain rhythms and their link to "psychic functions." Since that time, no one else has either. Later research centered around the more practical applications of the EEG to epilepsy, brain metabolism, brain functions and the levels of consciousness.

A frequency is the number of times a wave repeats itself within a second. It can be compared to the frequencies that you tune into on your radio. If any of these frequencies are deficient, excessive, or difficult to access, our mental performance can suffer.
Animation courtesy of Dr. Dan Russell, Kettering University


The raw EEG has usually been described in terms of frequency bands: Gamma greater than 30(Hz) BETA (13-30Hz), ALPHA (8-12 Hz), THETA (4-8 Hz), and DELTA(less than 4 Hz).

For example : Our brain uses 13Hz (high alpha or low beta) for "active" intelligence. Often we find individuals who exhibit learning disabilities and attention problems having a deficiency of 13Hz activity in certain brain regions that effects the ability to easily perform sequencing tasks and math calculations.


What is the function of the various brainwaves?
It is well known that the brain is an electrochemical organ; researchers have speculated that a fully functioning brain can generate as much as 10 watts of electrical power. Other more conservative investigators calculate that if all 10 billion interconnected nerve cells discharged at one time that a single electrode placed on the human scalp would record something like five millionths to 50 millionths of a volt. If you had enough scalps hooked up you might be able to light a flashlight bulb.

Even though this electrical power is very limited, it does occur in very specific ways that are characteristic of the human brain. Electrical activity emanating from the brain is displayed in the form of brainwaves. There are four categories of these brainwaves, ranging from the most activity to the least activity. When the brain is aroused and actively engaged in mental activities, it generates beta waves. These beta waves are of relatively low amplitude, and are the fastest of the four different brainwaves. The frequency of beta waves ranges from 15 to 40 cycles a second. Beta waves are characteristics of a strongly engaged mind. A person in active conversation would be in beta. A debater would be in high beta. A person making a speech, or a teacher, or a talk show host would all be in beta when they are engaged in their work.

This brainwave is also the normal waking consciousness. It is characterized as the state of being awake, alert, and concentrating. If this state is maintained for a prolonged period, it becomes associated with feelings of tension, worry, fear, or anxiety. Lower brain states are necessary on an occasional basis to maintain the alert aspect of this state. A visual-identification in the mind's eye occurs, a state where image are identified with form and specific objects.

Amplitude represents the power of electrical impulses generated by the brain.

Volume or intensity of brain wave activity is measured in microvolts.

"Gentlemen, I have a confession to make - half of what we have taught you is in error; and furthermore we cannot tell you which half it is."
--Sir William Osler
(to a graduating medical class)

The next brainwave category in order of frequency is alpha. Where beta represented arousal, alpha represents non-arousal. Alpha brainwaves are slower, and higher in amplitude. Their frequency ranges from 9 to 14 cycles per second. A person who has completed a task and sits down to rest is often in an Alpha state. A person who takes time out to reflect or meditate is usually in an Alpha state. A person who takes a break from a conference and walks in the garden is often in an Alpha state.


One of the main purposes for sleep is to transfer information and experiences from short to long-term memory. Concentration, learning and recall ability can and is greatly enhanced with alpha-theta control systems. Recall capability is greatest in alpha state. Also, by learning to exclude all external stimuli when trying to achieve the alpha-theta control, increases one's ability to concentrate.

The next state, Theta brainwaves, are typically of even greater amplitude and slower frequency. This frequency range is normally between 5 and 8 cycles a second. A person who has taken time off from a task and begins to daydream is often in a Theta brainwave state. A person who is driving on a freeway, and discovers that they can't recall the last five miles, is often in a theta state--induced by the process of freeway driving. The repetitious nature of that form of driving compared to a country road would differentiate a Theta state and a beta state in order to perform the driving task safely.

This state is traditionally labeled unconscious by western medicine. In recent years, however, people trained with light and sound tools and biofeed back can achieve this state and retain consciousness, similar to meditators. Theta has come to be associated with such things as hypnogogic imagery, day dreaming, sleep, and creativity. It has also been shown as the state where healing and regenerating of tissue occurs.

Two tuning forks of the same pitch will both resonate at the same frequency when one is struck. Brains operate much like a resonance chamber. Oscillating pulses and patterns of neural excitations ripple through our brains

nimation courtesy of Dr. Dan Russell, Kettering University

Theta is the brain state where magic happens in the crucible of your own neurological activity. Theta brings forward heightened receptivity, flashes of dreamlike imagery, inspiration, and your long-forgotten memories. Theta can bring you deep states of meditation. A sensation of "floating." And, because it is an expansive state, in Theta, you may feel your mind expand beyond the boundaries of your body.

Theta rests directly on the threshold of your subconscious. In biofeedback, it is most commonly associated with the deepest levels of meditation. Theta also plays an important part in behavior modification programs and has been used in the treatment of drug and alcohol addiction. Finally, Theta is an ideal state for super-learning, re-programming your mind, dream recall, and self-hypnosis.

Several companies use forms of brainwave entrainment technology. Robert Monroe, known for his journeys out of the body, studied altered states of consciousness and with his team of researchers and scientists have expanded knowledge about it

Theta waves range between 4-8 HZ. Theta is one of the more elusive and extraordinary realms we can explore. It is also known as the twilight state which we normally only experience fleetingly as we rise up out of the depths of delta upon waking, or drifting off to sleep. In Theta, we are in a waking dream, vivid imagery flashes before the mind's eye and we are receptive to information beyond our normal conscious awareness. Theta has also been identified as the gateway to learning and memory. Theta meditation increases creativity, enhances learning, reduces stress and awakens intuition and other extrasensory perception skills.


The Shamanic State of Consciousness, which is theta brainwaves, allows a journey into the higher planes. The steady-rhythmic beat of the drum struck four and one-half times per second (theta waves are 4-7 cps) is the key to transporting a shaman into the deepest part of his or her Shamanic trance. The constant and rhythmic-drone of Tibetan Buddhist chants that transport the monks and other listeners into realms of blissful meditation also follow this rhythm.

Light and Sound machines can help one attain this state...

The EEG (electroencephalograph) measures brainwaves of different frequencies within the brain. Electrodes are placed on specific sites on the scalp to detect and record the electrical impulses within the brain

Electrical Activity

The electrical activity of the brain behaves like any other electrical system. Changes in membrane polarization, inhibitory and excitatory post synaptic potentials, action potentials etc. create voltages that are conducted through the brain tissues. These electrical voltages enter the membranes surrounding the brain and continue up through the skull and appear at the scalp which are measured as microVolts.

These potentials are recorded by an electrode that is attached to the scalp with non-toxic conductive gel. The electrodes are fed into a sensitive amplifier.




The cerebral cortex is the outermost part of the brain. It is this convoluting mass of tissue that gives man superior intelligence. The cortex of each hemisphere is divided into four main areas, called lobes. Alpha is found predominantly on the occipital lobe or back-part of the brain. This is the section which deals with visual systems. Alpha is also found in the frontal lobe, but not as easily. Theta is found more commonly on the temporal lobe, while the speech, sensory, and motor areas tend to show primarily beta activity.

Individuals who do a lot of freeway driving often get good ideas during those periods when they are in Theta. Individuals who run outdoors often are in the state of mental relaxation that is slower than alpha and when in Theta, they are prone to a flow of ideas. This can also occur in the shower or tub or even while shaving or brushing your hair. It is a state where tasks become so automatic that you can mentally disengage from them. The ideation that can take place during the Theta state is often free flow and occurs without censorship or guilt. It is typically a very positive mental state.

Alpha-theta neurotherapy has demonstrated what the research team of Elmer and Alyce Green and Dale Walters at The Menninger Foundation said in the 1970s: Causing the brain to generate theta activity daily over a period of time seems to have enormous benefits, including boosting the immune system, enhancing creativity, and triggering or facilitating "integrative experiences leading to feelings of psychological well-being." The protocol seems to transcend the patient's lack of motivation to change, initial incapacity to create internal visual imagery, and/or disbelief in the effectiveness of the treatment. Frequently a patient's experience and results far exceed the goals targeted (in the visual imagery).

The reverie state which is indicated by theta and low-frequency alpha seems to increase hypnagogic and dream-like images. There is also a link between reverie and hypnagogic imagery and creativity. These images are critical for the creative process.

Scientists are learning more about how theta states can be summoned and harnessed to create mindstates that are conducive to expanded states of consciousness. Great ideas occur during this time period. Einstein came up with the theory of relativity in this state, and likewise, one of the Watson and Crick pair visualized the double helix in this mindstate successfully cracking the illusive architecture of DNA.


By merging both hemispheres of the brain, and allowing them to work together you can increase mental fitness (like having a faster modem working at faster speeds). A more integrated system creates better performance. Edgar Cayce, a famous clairvoyant healer was found to have an unusually large corpus callosum

Each time you push the skin in a circle imagining the face of a clock, the intuitive side is engaged, because imagining or visualizing as well as the actual movement have to do with the intuitive. When you "see in your mind's eye" the numbers on the clock, the logical is activated because numbers have to do with logical thinking.


The Theta state is where intuition comes, instantaneous healings occur and accelerated learning occurs. Einstein trained himself to spend many hours in that state. It is where you feel one with All.

The final brainwave state is Delta. Here the brainwaves are of the greatest amplitude and slowest frequency. They typically center around a range of 1.5 to 4 cycles per second. They never go down to zero because that would mean that you were brain dead. But, deep dreamless sleep would take you down to the lowest frequency. Typically, 2 to 3 cycles a second.

When we go to bed and read for a few minutes before attempting sleep, we are likely to be in low beta. When we put the book down, turn off the lights and close our eyes, our brainwaves will descend from beta, to alpha, to theta and finally, when we fall asleep, to delta.
It is a well known fact that humans dream in 90 minute cycles. When the delta brainwave frequencies increase into the frequency of theta brainwaves, active dreaming takes place and often becomes more experiential to the person. Typically, when this occurs there is rapid eye movement, which is characteristic of active dreaming. This is called REM, and is a well known phenomenon.


Hypnosis subjects are much more susceptible to suggestion when in lower alpha states. It is now possible to achieve states of consciousness within several weeks of training equivalent to those of Zen masters with 20 years meditation effort.
Nova Pro 100
Inner Pulse

When an individual awakes from a deep sleep in preparation for getting up, their brainwave frequencies will increase through the different specific stages of brainwave activity. That is, they will increase from delta to theta and then to alpha and finally, when the alarm goes off, into beta. If that individual hits the snooze alarm button they will drop in frequency to a non-aroused state, or even into theta, or sometimes fall back to sleep in delta. During this awakening cycle it is possible for individuals to stay in the theta state for an extended period of say, five to 15 minutes--which would allow them to have a free flow of ideas about yesterday's events or to contemplate the activities of the forthcoming day. This time can be an extremely productive and can be a period of very meaningful and creative mental activity.

In summary, there are four brainwave states that range from the high amplitude, low frequency delta to the low amplitude, high frequency beta. These brainwave states range from deep dreamless sleep to high arousal. The same four brainwave states are common to the human species. Men, women and children of all ages experience the same characteristic brainwaves. They are consistent across cultures and country boundaries.

Research has shown that although one brainwave state may predominate at any given time, depending on the activity level of the individual, the remaining three brain states are present in the mix of brainwaves at all times. In other words, while somebody is an aroused state and exhibiting a beta brainwave pattern, there also exists in that person's brain a component of alpha, theta and delta, even though these may be present only at the trace level.

DELTA brainwaves are your unconscious mind, the sleep state, but when present in combination with other waves in a waking state, Delta acts as a form of radar – seeking out information – reaching out to understand on the deepest unconscious level things that we can't understand through thought process. Delta provides intuition, empathetic attunement, and instinctual insight."

"Someone in an Awakened Mind state (specific activation of beta, alpha, theta and delta in both hemispheres) has access to the unconscious empathy, intuition, and radar of the delta waves, the subconscious creative storehouse, inspiration and spiritual connection of the theta waves, the bridging capacity, lucidity and vividness of imagery, and relaxed detached awareness of the alpha waves, and the ability to consciously process thoughts in beta – all at the same time!"

Mind machines are a device that allows you to modify your brain wave states.
Frequency following response (FFR) also referred to as brain wave entertainment was discovered in the 1930s. Doctors began recording the brain's electrical activity with electrodes placed on the scalp and with electroencephalograph (EEG) devices.

After the development of the EEG, scientists Adrian and Matthews discovered that repetitive light and sound frequencies were a stimulus to which brain wave activity would react and respond. Various psychologist and researchers used this information for brain wave synchronization (BWS) experiments and therapies. A noticeable and outstanding result was the ability to self-direct deep levels of relaxation and focused states of hypnosis.

About 1940, physiologist William Grey Walter discovered that at certain entrainment frequencies, his subjects would enter trance-like states, where they began to experience deep peacefulness, dream-like visions, and other unexpected sensations. In 1958, the first brain wave synchronizer (BWS) was introduced commercially by Sidney A Schneider. Today BWS is more popularly called a mind machine or a light and sound device.