Your brain is made up of billions of brain cells called neurons, which use electricity to communicate with each other. The combination of millions of neurons sending signals at once produces an enormous amount of electrical activity in the brain, which can be detected using sensitive medical equipment (such as an EEG), measuring electricity levels over areas of the scalp.
The combination of electrical activity of the brain is commonly called a brainwave pattern, because of its cyclic, "wave-like" nature.
Below is one of the first recordings of brain activity.1
Here is a more modern EEG recording:
With the discovery of brainwaves came the discovery that electrical activity in the brain will change depending on what the person is doing. For instance, the brainwaves of a sleeping person are vastly different than the brainwaves of someone wide awake. Over the years, more sensitive equipment has brought us closer to figuring out exactly what brainwaves represent and with that, what they mean about a person's health and state of mind.
Here is a table showing the known brainwave types and their associated mental states:
Associated Mental State
|Gamma||27 Hz and up||
Gamma is associated with the formation of ideas, language and memory processing, and various types of learning. 2 3 4 Gamma waves have been shown to disappear during deep sleep induced by anesthesia, but return with the transition back to a wakeful state.5 6
|Beta||12hz - 27hz||
Wide awake. This is generally the mental state most people are in during the day and most of their waking lives. Usually, this state in itself is uneventful, but don't underestimate its importance. Many people lack sufficient beta activity, which can cause mental or emotional disorders such as depression and ADD.7 8 and insomnia. And low SMR production (a sub-range of beta at 12-15hz) may be related to insomnia.9 Stimulating beta activity can improve emotional stability, energy levels, attentiveness and concentration.10 11 12
|Alpha||8hz - 12hz||
Awake but relaxed and not processing much information. When you get up in the morning and just before sleep, you are naturally in this state. When you close your eyes your brain automatically starts producing more alpha waves.
Many studies monitoring the EEG activity of experienced meditators have revealed strong increases in alpha activity.13 Alpha activity has also been connected to the ability to recall memories, lessened discomfort and pain, and reductions in stress and anxiety.14 15 16 17
|Theta||3hz - 8hz||
Light sleep or extreme relaxation.
|Delta||0.2hz - 3hz||Deep, dreamless sleep. Delta is the slowest band of brainwaves. When your dominant brainwave is delta, your body is healing itself and "resetting" its internal clocks.20 You do not dream in this state and are completely unconscious.|
For more information about each brainwave frequency, and the corresponding benefits of stimulation at that frequency, check out our infographic series. These images contain an in-depth overview of some of the most significant, peer-reviewed research into the benefits of brainwave entrainment.
The Significance of Brainwaves
You can tell a lot about a person simply by observing their brainwave patterns. For example, anxious people tend to produce an overabundance of high beta waves while people with ADD/ADHD tend to produce an overabundance of slower alpha/theta brainwaves.
Researchers have found that not only are brainwaves representative of of mental state, but they can be stimulated to change a person's mental state, and this in turn can help with a variety of mental issues.
1. Berger, H. (1929). Über das elektrenkephalogramm des menschen. European Archives of Psychiatry and Clinical Neuroscience, 87(1), 527-570.
2. Crone, N. E., Hao, L., Hart, J., Boatman, D., Lesser, R. P., Irizarry, R., & Gordon, B. (2001). Electrocorticographic gamma activity during word production in spoken and sign language. Neurology, 57(11), 2045-2053.
3. Burle, B., & Bonnet, M. (2000). High-speed memory scanning: a behavioral argument for a serial oscillatory model. Cognitive Brain Research, 9(3), 327-337.
4. Miltner, W. H., Braun, C., Arnold, M., Witte, H., & Taub, E. (1999). Coherence of gamma-band EEG activity as a basis for associative learning. Nature,397(6718), 434-436.
5. John, E. R., Prichep, L. S., Kox, W., Valdes-Sosa, P., Bosch-Bayard, J., Aubert, E., & Gugino, L. D. (2001). Invariant reversible QEEG effects of anesthetics. Consciousness and cognition, 10(2), 165-183.
6. Munk, M. H., Roelfsema, P. R., König, P., Engel, A. K., & Singer, W. (1996). Role of reticular activation in the modulation of intracortical synchronization.Science, 272(5259), 271-274.
7. Brenner, R. P., Ulrich, R. F., Spiker, D. G., Sclabassi, R. J., Reynolds III, C. F., Marin, R. S., & Boller, F. (1986). Computerized EEG spectral analysis in elderly normal, demented and depressed subjects. Electroencephalography and clinical neurophysiology, 64(6), 483-492.
8. Egner, T., & Gruzelier, J. H. (2004). EEG biofeedback of low beta band components: frequency-specific effects on variables of attention and event-related brain potentials. Clinical Neurophysiology, 115(1), 131-139.
9. Hauri, P. (1981). Treating psychophysiologic insomnia with biofeedback.Archives of General Psychiatry, 38(7), 752.
10. Siever, D. (2004). The application of audio-visual entrainment for the treatment of seasonal affective disorder. Biofeedback, 32 (3), 32-35.
11. Howard CE, Graham LE, 2nd, Wycoff SJ. A comparison of methods for reducing stress among dental students. J Dent Educ. 1986;50(9):542-544
12. Patrick GJ. Improved neuronal regulation in ADHD: An application of 15 sessions of photic-driven EEG neurotherapy. J Neurother. 1996;1(4):27-36.
13. Cahn BR, Polich J. Meditation states and traits: EEG, ERP, and neuroimaging studies. Psychol Bull. 2006 Mar;132(2):180-211.
14. Williams, J., Ramaswamy, D. and Oulhaj, A., 2006. 10 Hz flicker improves recognition memory in older people. BMC Neurosci. 7, 21.
15. Williams JH. Frequency specific effects of flicker on recognition memory. Neuroscience. 2001;104(2):283-286
16. Nomura T, Higuchi K, Yu H, et al. Slow-wave photic stimulation relieves patient discomfort during esophagogastroduodenoscopy. J Gastroenterol Hepatol. 2006;21(1 Pt 1):54-58
17. Ossebaard HC. Stress reduction by technology? An experimental study into the effects of brainmachines on burnout and state anxiety. Appl Psychophysiol Biofeedback. 2000;25(2):93-101
18. Wickramasekera I, I. E. (1977). On attempts to modify hypnotic susceptibility: Some psychophysiological procedures and promising directions. Annals of the New York Academy of Sciences, 296, 143-153
19. Sabourin, M. E., Cutcomb, S. D., Crawford, H. J., & Pribram, K. (1990). EEG correlates of hypnotic susceptibility and hypnotic trance: spectral analysis and coherence. International Journal of Psychophysiology, 10(2), 125-142.
20. Botella-Soler, V., Valderrama, M., Crépon, B., Navarro, V., & Le Van Quyen, M. (2012). Large-scale cortical dynamics of sleep slow waves. PloS one, 7(2), e30757.