Our brains are made up of billions of brain cells called neurons. Neurons 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 our brains, which can be detected using sensitive medical equipment such as an EEG (Electroencephalograph), measuring electricity levels over areas of the scalp. Because of its cyclic, wave-like nature, the combination of electrical activity of the brain is commonly called a brainwave pattern.

Brainwave Frequencies

Brainwave speed is measured in Hertz (cycles per second) and can be categorized into five main groups – Gamma, Beta, Alpha, Theta and Delta.1 For each category we have presented broadly descriptions, because in practice things are far more complex than that, and brainwaves reflect many different aspects when they occur in different locations in the brain and different circumstances.

27Hz to 50Hz

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

12Hz to 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

8Hz to 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

3Hz to 8Hz

Light sleep or extreme relaxation. Theta is also a very receptive mental state that has proven useful for hypnotherapy, as well as self-hypnosis using recorded affirmations and suggestions.18 19

0.2Hz to 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.

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