Brainwave Frequencies
We’ve all experienced that magical feeling of being hit with ‘a brainwave’. That moment of newfound clarity, a shift in perspective, or a novel idea. And typically, it seems to appear out of nowhere. In between sips of coffee, while out for a walk, or simply indulging your dog in a good belly rub.
While “a brainwave” can be a figure of speech to describe our thoughts, scientists and clinicians can use literal brainwaves, measured on the head, to help understand the functioning of the human brain. As it turns out, the key to having more of these ‘aha’ moments lies in understanding the science behind brainwaves. Neuroscientists have been studying brainwaves – the popular name for the field of electroencephalography – for nearly a century.
What are brainwaves?
The brain has billions of neurons, and each individual neuron connects (on average) to thousands of others. Communication happens between them through small electrical currents that travel along the neurons and throughout enormous networks of brain circuits. When all these neurons are activated they produce electrical pulses – visualize a wave rippling through the crowd at a sports arena – this synchronized electrical activity results in a “brainwave”.
When many neurons interact in this way at the same time, this activity is strong enough to be detected even outside the brain. By placing electrodes on the scalp, this activity can be amplified, analyzed, and visualized. This is electroencephalography, or EEG – a fancy word that just means an electric brain graph. (Encephalon, the brain, is derived from the ancient Greek “enképhalos,” meaning within the head.)
One way that EEG ‘brainwaves’ convey information is in their rate of repetition. Some oscillations, measured on the scalp, occur at more than 30 cycles per second (and up to 100 cycles per second!) These cycles, also called frequencies, are measured as Hz, or hertz, after the scientist who proved the existence of electromagnetic waves.
When looked at this way, brainwaves come in five flavors, each of which corresponds to a Greek letter. As we’ll see, these different brainwaves correspond to different states of thought or experience. While there are many other ways to analyze brainwaves, many practitioners of a field called neurofeedback rely on dividing brain oscillations into these five categories.
Some of these brain oscillations are more easily detectable on specific parts of the scalp, corresponding to the parts of the brain just below. The brain has many specialized regions that correspond to different processes, thoughts, and sensations. Particular oscillations often reflect distinct regions and networks in the brain communicating with each other.
The 5 Main Types of Brainwave Frequencies
Different patterns of brainwaves can be recognized by their amplitudes and frequencies. Brainwaves can then be categorized based on their level of activity or frequency. It’s important to remember, though, that brainwaves are not the source or the cause of brain states, or of our experiences of our own minds – they’re just some of the detectable reflections of the complex processes in the brain that produce our experience of being, thinking, and perceiving.
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Slow activity refers to a lower frequency and high amplitude (the distance between two peaks of a wave). These oscillations are often much larger in amplitude (wave depth). Think: low, the deep beat of a drum.
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Fast activity refers to a higher frequency and often smaller amplitude. Think high-pitched flute.
Below are five often-described brainwaves, from the fastest activity levels to the slowest.
Delta Brainwaves
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Frequency: 0.5-4 Hz
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State: Sleep, dreaming
These are the slowest of all brainwaves and are strongest when we are enjoying restorative sleep in a dreamless state. This is also the state where healing and rejuvenation are stimulated, which is why it’s so crucial to get enough sleep each night. It is the dominant rhythm in infants up to one year of age and it is present in stages 3 and 4 of sleep.
Theta Brainwaves
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Frequency: 4-8 Hz
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State: Creativity, insight, dreams, reduced consciousness
According to Professor Jim Lagopoulos of Sydney University, “previous studies have shown that theta waves indicate deep relaxation and occur more frequently in highly experienced meditation practitioners. The source is probably frontal parts of the brain, which are associated with monitoring of other mental processes.”
Most frequently, theta brainwaves are strongly detectable when we’re dreaming in our sleep (think, the movie Inception), but they can also be seen during:
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Deep meditation
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Daydreaming
When we’re doing a task that is so automatic that the mind can disengage from it e.g. brushing teeth, showering. Research has also shown a positive association of theta waves with memory, creativity, and psychological well-being.
Alpha Brainwaves
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Frequency: 8-13 Hz
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State: Physically and mentally relaxed
Alpha brainwaves are some of the most easily observed and were the first to be discovered. They become detectable when the eyes are closed and the mind is relaxed. Good healthy alpha production promotes mental resourcefulness, aids in the ability to mentally coordinate, enhances the overall sense of relaxation and fatigue. In this state, you can move quickly and efficiently to accomplish whatever task is at hand. When Alpha predominates most people feel at ease and calm.
They can also often be found during activities such as:
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Yoga
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Just before falling asleep
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Being creative and artistic
Beta Brainwaves
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Frequency: 13-32 Hz
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State: Alert, normal alert consciousness, active thinking
Beta brainwaves are generally regarded as a normal rhythm and are the dominant rhythm in those who are alert or anxious or who have their eyes open. It is the state that most of the brain is in when we have our eyes open and are listening and thinking during analytical problem solving, judgment, decision making, processing information about the world around us.
The beta band has a relatively large range and has been divided into low, midrange, and high.
LOW BETA (12-15HZ):
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Subjective feeling states: relaxed yet focused, integrated
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Associated tasks & behaviors: low SMR can reflect “ADD”, lack of focused attention
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Physiological correlates: is inhibited by motion; restraining body may increase SMR
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Effects of Training: increasing SMR can produce relaxed focus, improved attentive abilities
MID BETA (15-18hz):
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Subjective feeling states: thinking, aware of self & surroundings
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Associated tasks & behaviors: mental activity
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Physiological correlates: alert, active, but not agitated
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Effects of Training: can increase mental ability, focus, alertness
HIGH BETA (above 18hz):
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Subjective feeling states: alertness, agitation
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Associated tasks & behaviors: mental activity, e.g. math, planning
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Physiological correlates: general activation of mind & body functions.
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Effects of Training: can induce alertness, but may also produce agitation
Gamma Brainwaves
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Frequency: 32 – 100 Hz
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Associated state: Heightened perception, learning, problem-solving tasks
Gamma brainwaves are the fastest measurable EEG brainwaves and have been equated to ‘heightened perception’, or a ‘peak mental state’ when there is simultaneous processing of information from different parts of the brain. Gamma brainwaves have been observed to be much stronger and more regularly observed in very long-term meditators including Buddhist Monks.
How to Train Your Brainwaves
Is it possible to change how much we experience these different brainwaves, and the brain states and thought experiences associated with them? In short, yes.
Conditioning and Neurofeedback
For decades, practitioners have engaged in training programs that are intended to reinforce the brain states which produce increases in certain brain oscillations and decreases in others. The most common example of this, called neurofeedback, can utilize EEG or other brain-sensing modalities.
Neurofeedback practitioners and clinicians find that immediate, direct feedback on brain states, whether in the form of sound, light, or even a video game, can produce changes in underlying behaviors and brain states that are reflected in brainwaves. This feedback seems to accelerate the learning process, by making brain states more apparent to the recipient.
Another important discovery in the recent history of neuroscience is the significant differences in brainwave characteristics of highly experienced meditators. Expert meditators not only have different resting-state brainwaves from non-meditators – but they also seem able to control their brainwaves through voluntary thought control with greater ease than others.
So how do we start to improve our ability to control our brainwaves? These brainwave-changing skills can be learned. Meditation deepens your ability to focus and control your attention.
References
Scientific American. (2018). What is the function of the various brainwaves?. [online] Available at: https://www.scientificamerican.com/article/what-is-the-function-of-t-1997-12-22/ [Accessed 26 Feb. 2018].
Lustenberger, C., Boyle, M., Foulser, A., Mellin, J. and Fröhlich, F. (2015). The functional role of frontal alpha oscillations in creativity. Cortex, [online] 67, pp.74-82. Available at: https://www.sciencedirect.com/science/article/pii/S0010945215001033 [Accessed 26 Feb. 2018].
ScienceDaily. (2018). Alpha waves close your mind for distraction, but not continuously, research suggests. [online] Available at: https://www.sciencedaily.com/releases/2012/10/121008134058.htm [Accessed 26 Feb. 2018].
Haarmann, H., George, T., Smaliy, A. and Dien, J. (2012). Remote Associates Test and Alpha Brain Waves. The Journal of Problem Solving, [online] 4(2). Available at: https://docs.lib.purdue.edu/jps/vol4/iss2/5/ [Accessed 26 Feb. 2018].
Buzsáki, G. (2002). Theta Oscillations in the Hippocampus. Neuron, [online] 33(3), pp.325-340. Available at: https://www.sciencedirect.com/science/article/pii/S089662730200586X [Accessed 26 Feb. 2018].
White, N. (1999). Theories of the Effectiveness of Alpha-Theta Training for Multiple Disorders. Introduction to Quantitative EEG and Neurofeedback. pp 341-367. Available at: https://www.sciencedirect.com/science/article/pii/B9780122437908500146 [Accessed 26 Feb. 2018].
Brainworksneurotherapy.com. (2018). What are Brainwaves? Types of Brain waves | EEG sensor and brain wave – UK. [online] Available at: http://www.brainworksneurotherapy.com/what-are-brainwaves [Accessed 26 Feb. 2018].
Marzbani, H., Marateb, H. R., & Mansourian, M. (2016). Neurofeedback: a comprehensive review on system design, methodology, and clinical applications. Basic and Clinical Neuroscience, 7(2), 143-158. http://dx.doi.org/10.15412/J.BCN.03070208
Calomeni, Mauricio Rocha, et al. “Modulatory Effect of Association of Brain Stimulation by Light and Binaural Beats in Specific Brain Waves.” Clinical Practice & Epidemiology in Mental Health, benthamopen.com/FULLTEXT/CPEMH-13-134.