The electrical activity emanating from the brain creates frequencies called brainwaves. Brainwave frequencies are measured in Hertz (Hz), meaning cycles per second. The more cycles per second, the greater the Hertz value.
There are four major categories of brainwaves ranging from the most activity to the least activity, these are: BETA, ALPHA, THETA and DELTA.
Each image below depicts a one second snapshot of human brainwave activity, as detected by an electroencephalogram (EEG). As you’ll notice, greater values indicate more brainwave activity within the one second time-frame.
BETA BRAINWAVES are characteristic of an engaged mind, which is highly alert and well focused. Beta activity is quick-connect, fast activity and tends to dominate the normal waking state of consciousness when-attention is directed towards the outside world.
Typically detected in the frontal lobes (where decisions are managed), Beta is usually seen on both sides of the brain in geometric distribution. It may be absent or reduced in areas of brain damage. It is generally regarded as a normal rhythm and tends to be the dominant rhythm in those who are alert, anxious or have their eyes open
ALPHA BRAINWAVES are slower than beta and can represent a relaxed awareness in the mind. This rhythm is seen when the brain sets itself to rest or reflect. Alpha rates are increased by closing the eyes and relaxation, yet are offset by opening one’s eyes or any concentrated effort.
Alpha is usually best detected in the frontal regions of the head, on each side of the brain. Alpha is the major rhythm seen in normal relaxed adults and is typically regarded as the common relaxation mode beyond the age of 13.
THETA BRAINWAVES can indicate drowsiness, daydreaming, the first stage of sleep or ‘indirect’ imagination/thinking. Theta activity is not often seen in awake adults (unless engaged in a meditative practice), but is perfectly normal in alert children up to 13 years and in most sleep.
A Theta state can be regarded as a gateway to hypnagogic states that lay between being awake and falling asleep. Often Theta entrainment can promote vivid flashes of mental imagery as one becomes receptive to brain/mind information beyond one’s typical conscious awareness. Theta has also been identified as a part of learning, memory and reductions in stress.
DELTA BRAINWAVES can reveal deep sleep or slow-wave ‘background’ thinking. Much like bass sound, Delta tends to be the highest in amplitude and the slowest waves. Delta is often associated with deep sleep. Certain frequencies, in the delta range, have been shown to trigger the body’s healing and growth mechanisms.
Interestingly, Delta is the dominant rhythm in infants up to one year, as well as stages 3 and 4 of dreamless sleep.