This following is adapted from a wide variety of sources, principle among them, Wikipedia, The Physics Factbook, Brainwaves and Scientific American [my emphasis throughout]:
"Brain waves are produced by the extremely low voltages involved in transmitting messages among neurons. Most conscious activity produces beta waves at 13 to 30 hertz, or cycles per second. More intense gamma waves (30 to 60 or even 90 Hz) generally mark complex operations such as memory storage and sharp concentration" [SA]
There are four principal brain wave states that range from high amplitude, low frequency delta through to the low amplitude, high frequency beta. These states range from deep dreamless sleep to a state of high arousal. These four brain wave states are common throughout humans. All levels of brain waves exist in everyone at all times, even though one is foregrounded depending on the activity level. When a person is in an aroused state and exhibiting a beta brain wave pattern, their brain also exhibits a component of alpha, theta and delta, even though only a trace may be present. [wiki]
"As is well recognized, however, various subsets exist in all EEG frequency bands."[src]
"Remember this: gently boosting the electrical waves in the brain can improve memory. German researchers found that by running a weak electrical current through the brain of sleeping medical students, they could improve their performance on a word-recall task. The finding represents the first evidence that slow oscillations generated by groups of neurons in the brain are not simply a by-product of neural activity but rather critical to the formation of memory." [SA]
"Finally, the fact that brain rhythms may have functional implications for the working of neural networks is examined in relation to 2 cases: the possibility that oscillations may subserve a gating function, and that oscillations may play a role in the formation of assemblies of neurons that represent given stimulus patterns." [src]
“Acoustic work, like composition from memory, silent reading, and mental arithmetic all require and induce the faster brain wave production. Literate activity, reading, writing and talking carefully, are activities that provide a sufficiently chaotic base to experience - that there is always the tendency for these activities to complexify further and speed up the brain.” [src]
Upon waking from a deep sleep in preparation for arising, your brain wave frequencies increase through the different stages of brain wave activity, moving from delta to theta and then to alpha and into beta. [wiki]
"The Brain also tries to match artificial man made signals. Higher frequency (above 12 Hz) trigger extra serotonin [increases] and melatonin [decreases] production in the brain. Most electric appliances work off of 60 Hz or higher in North America and 50 Hz in Europe. Computer monitors operate at 20,000 Hz., Cellular Phones operate a 840 Million Hz., Microwave Ovens at 2.8 Billion Hz. Scary eh! The higher the frequency the more serotonin that's produced in the brain." [src]
"As known, different brainwave frequencies show synchronies related to different perceptual, motor or cognitive states. Brainwaves have also been shown to synchronize with external stimuli with repetition rates of ca. 10–40 Hz. However, not much is known about responses to periodic auditory stimuli with periodicities found in human rhythmic behavior (i.e. 0.5–5 Hz). In an EEG study we compared responses to periodic stimulations (drum sounds and clicks with repetition rates of 1–8 Hz), silence, and random noise. Here we report inter-trial coherence measures taken at the Cz-electrode that show a significant increase in brainwave synchronization following periodic stimulation. Specifically, we found (1) a tonic synchronization response in the delta range with a maximum response at 2 Hz, (2) a phasic response covering the theta range, and (3) an augmented phase synchronization throughout the beta/gamma range (13–44 Hz) produced through increased activity in the lower gamma range and modulated by the stimulus periodicity. Periodic auditory stimulation produces a mixture of evoked and induced, rate-specific and rate-independent increases in stimulus related brainwave synchronization that are likely to affect various cognitive functions. The synchronization responses in the delta range may form part of the neurophysiological processes underlying time coupling between rhythmic sensory input and motor output; the tonic 2 Hz maximum corresponds to the optimal tempo identified in listening, tapping synchronization, and event-interval discrimination experiments. In addition, synchronization effects in the beta and gamma range may contribute to the reported influences of rhythmic entrainment on cognitive functions involved in learning and memory tasks." [src]
State [src] Frequency range State of mind
Delta 0.5Hz - 4Hz Deep sleep
Theta 4Hz - 8Hz Drowsiness
Alpha 8Hz - 14Hz Relaxed but alert
Beta 14Hz - 30Hz Highly alert and focused
Gamma 40 Hz Higher mental activity
Gamma Waves have the highest range of frequencies (around 40 Hz) and are involved in higher mental activity. They have also been detected during the process of awakening and during active rapid eye movement (REM) sleep. [wiki]
"Regular deep meditation changes the brain in positive ways. This type of meditation seems to be associated with gamma waves, the electromagnetic rhythm of neurons firing very rapidly in harmony. Neuroscientists have pinpointed the cells responsible for producing these gamma rhythms and demonstrated a technology that can induce the brain-wave pattern in mice." [SA]
"Researchers at the University of Wisconsin-Madison have found that during meditation, Zen Buddhist monks show an extraordinary synchronization of brain waves known as gamma synchrony--a pattern increasingly associated with robust brain function and the synthesis of activity that we call the mind." [SA]
Beta Waves are the most common of the brain wave patterns that occur when awake. These occur during period of intense concentration, problem solving, and focused analysis. The frequency of beta waves is between 13–30 Hz (cycles per second). [wiki]
"Beta Brainwaves kick in when we think logically, solve problems, and confront external stimuli. Beta often races and brings panic at times. Used too often, you run the risk of thinking deeply about little, and tiring yourself out about much…Beta has it’s place but must be helped to slow down at times and reflect." [src]
"However, too much Beta can cause significant problems for the individual by increasing muscle tension, raising blood pressure, and creating a state of anxiety for the individual. While it is possible to teach the highest level cognitive processing and complex artistic expression, attention must also be paid to assist the individual in achieving a degree of physical relaxation." [src]
"According to the Smell and Taste Research Center in Chicago, just getting a whiff of peppermint can dramatically increase the brain's production of beta-waves. However to really trigger your beta-waves you should chew peppermint gum, not just sniff it. This is because 90% of it's odor will quickly rise to the back of your throat and in to your nose. This raises your beta-wave production in less than a minute!" [src]
SMR (Sensorimotor Response) or Low Beta Brainwaves - (12-15 Hz)
"Distribution: localized by side and by lobe (frontal, occipital, etc)
Subjective feeling states: relaxed yet focused, integrated
Associated tasks and behaviors: low SMR can reflect "ADD", lack of focused attention
Physiological correlates: is inhibited by motion; restraining body may increase SMR
Effects of Training: increasing SMR can produce relaxed focus, improved attentive abilities." [src]
"The animal entered a unique state--it remained absolutely still, though extremely alert, waiting for the tone to end. It is the same state a house cat waits in, feigning heavy-lidded indifference, as a bird makes its way near enough to be pounced on." A Symphony in the Brain by Jim Robbins.
Alpha Waves are any of the electrical waves from the parietal and occipital regions of the brain, having frequencies from 8 to 12 hertz (cycles per second). Some scientists consider the range 8–13 Hz and are most usual when we are mentally alert, calm and relaxed, or when day-dreaming. Alpha waves are a sign of relaxation, as they indicate a lack of sensory stimulation in a conscious person. [wiki]
"Alpha Brainwaves add images and visuals; you could view this as escape from reality. Too much alpha activity leads to excessive escapes and too many daydreams. Too little makes us human machines:– in motion, but without dreams that direct." [pdf]
"Our brain uses its 8 - 13 cycles per second Alpha waves to idle itself, to rest areas not actively processing and acting on incoming sensory and motor information. While this idling is a normal and favorable phenomenon for the idling brain, if Alpha wave activity becomes 'locked' and inhibited, active participation of vital brain areas cannot occur with efficiency." [src]
"Psychophysiologist Thomas Mulholland found that after just 30 seconds of watching television the brain begins to produce alpha waves, which indicates torpid (almost comatose) rates of activity. Alpha brain waves are associated with unfocused, overly receptive states of consciousness. A high frequency alpha wave does not occur normally when the eyes are open. In fact, Mulholland’s research implies that watching television is neurologically analogous to staring at a blank wall.
I should note that the goal of hypnotists is to induce slow brain wave states. Alpha waves are present during the 'light hypnotic' state used by hypno-therapists for suggestion therapy."[src]
Alpha-Theta State
“Many cultures discovered this and the methods to achieve this state naturally and artificially. Many of the worlds religions were founded on reaching this state and devised strict disciplines to do so. The Alpha-Theta range occurs during reverie, hypnogogic imagery, meditation, and by self-hypnosis." [src]
Theta Waves occur when we are mentally drowsy and unfocused, during deep calmness, most daydreaming, relaxation or tranquility, as for example we make the transitions from drowsiness to sleep or from sleep to the waking state. The frequency of theta waves is between 4–7 Hz (cycles per second) though some researchers regard theta to be 5 to 8 cps. [wiki]
In brain wave frequencies, theta is the frequency range where drowsiness, unconsciousness, dreaming states and deep tranquility happen. Most daydreaming occurs while in the theta range. It is normally a very positive mental state and prolonged states of the theta brain wave frequency while conscious can be extremely productive and a time of very meaningful/creative mental activity. [wiki]
With practice, meditation can also lower a person's brain wave frequency to theta while allowing the meditator to remain conscious. [wiki]
"The Emerys conclude, with impressive neuro-physiological evidence to back their claims concerning the function of Theta waves, that television is ‘a maladaptive technology,’ a technology that injures the health of the user. They set up a set of conditions showing the relationship between high Theta presence and low brain wave response in the situation of TV use…." [src]
"Theta Brainwaves engage inner and intuitive subconscious. You’ll find theta in places where you hold memories, sensations and emotions. Sometimes, we also store secrets there, which we block out in times of pain, to survive what we feel unprepared to fix." [pdf]
"The brain uses this state to exercise itself, somewhat like working out your muscles to make them stronger and to release overall tension. The drugs that promote this activity are, on the whole, illegal. These substances are in the general category of hallucinogens...." [src]
"Subset 2: According to Cavanaugh (1972), 4 Hz Theta is associated with object naming, an important aspect of memory." [src]
Theta/Beta Ratio
"Lubar's [Dr. Joel Lubar] major contribution to the field [of ADD] is the theta-to-beta ratio - that is, too much theta compared to beta, which can cause attention problems and hyperactivity. (It seems counter-intuitive that too much slow wave can cause a child to be hyperactive, but because the brain is operating too slowly and not getting enough stimuli, the child seeks external stimulation to reward his brain.)" A Symphony in the Brain by Jim Robbins.
Delta Waves occur primarily during deep sleep or states of unconsciousness. The frequency of delta waves is between 0.5–4 Hz (cycles per second). [wiki]
