You most likely already know that brainwave frequencies are grouped together into bands: delta, theta, alpha, beta and gamma.
Although boundary states between these bands exist, in this article I will focus on these five groups of brainwave frequencies and describe the mental states and functions associated with each group.

The 5 brainwave frequencies are:

Delta Waves

Brainwaves of a 4hz frequency or less are classed as delta waves. These are associated with deep sleep, and are thought to be generated by the thalamus (a part of the brain that integrates information from the different senses, and use it to direct attention). Most of a baby's brain activity is in the delta range, but by adulthood delta waves are no longer present when a person is awake.

Theta Waves

Brainwaves between 4 and 7hz are classed as theta waves. These are associated with REM (rapid eye movement) sleep, during which dreaming occurs. They are generated by the hippocampus, which is a part of the brain responsible for forming memories. They also appear during meditation. Delta and theta waves together make up the brainwave frequencies which appear during sleep.

Alpha Waves

Brainwaves between 8 and 12hz are classed as alpha waves. Alpha waves appear when an individual is relaxed, and are associated with associative thinking – daydreaming, for instance – and the imagination. Closing the eyes (whilst awake) causes an instant surge of alpha activity.

Beta Waves

Brainwaves between 12 and 30hz are classed as beta waves, and appear when an individual is alert and focused. They are associated with concentration, “busy thinking” and general movement. Alpha and beta waves together make up the brainwave frequencies which appear when an individual is awake. Alpha dominates when an individual is in a state of relaxation, and beta when an individual is in a state of alertness.

Gamma Waves

Brainwaves of a 40hz frequency or above are classed as gamma waves. Flashes of sudden insight or understanding (“a-ha” moments) are associated with sudden surges of gamma activity. High gamma wave activity is associated with above average intelligence, and children with high gamma activity have been found to have higher than average language abilities, cognitive skills and attention spans.

Experiments on Tibetan Buddhist monks have shown that long term meditation causes an overall increase in gamma wave activity – perhaps as a consequence of techniques which stress concentration and focus. In fact, there are many correspondences between meditative states and brainwave frequencies. However, those are to be covered in another article.

Author's Bio: 

Copyright © 2010 Edward Haycock. To find out more about brainwave frequencies and altered states, including the three boundary states, visit: