There are 4 basic brain wave frequencies and each correlates with a specific state of consciousness. Like sound frequencies, brain waves are measured in Hz, or cycles per second. In general, the slower the frequency of your brain waves, the more relaxed you feel.
Beta: 13-30 hz
Associated with attentiveness, selective attention, concentration & anticipation. They are related to concentrated mental activity such as solving math problems, anxiety, and apprehension.
Important points about Beta Waves
These are the waves of alertness, wakeful state. Most common and most prevalent in the brain. If you are alert and awake, you are in Beta now. In meditation, beta waves have been noticed only in very experienced practitioners that too in a state of ecstasy and concentration.
Alpha: 8-13 hz
Alpha is the brain wave associated with relaxed, daydreaming states of mind; it’s a state of relaxed, detached awareness. Many people are “in alpha” while watching TV. Alpha is often called a “hypnogogic” state because you may experience spontaneous mental imagery.
If you’re like most people, when you close your eyes and take a few slow, deep breaths you’ll experience a light, relaxed alpha state. Alpha is considered the gateway to meditation. Some people consider alpha waves to be the link between the conscious mind and the subconscious.
You produce alpha waves when you relax to guided imagery. Your brain also produces alpha waves just before you drift off to sleep and just before you wake up. At the beginning of “stage 1 sleep” alpha waves disappear and theta waves appear.
Important points about Alpha Waves
Considered as the brainwaves of meditation. Most prominent during meditation.
Considered as an important part of the relaxation process before sleep. The alpha frequency band has been studied extensively in meditations of various kinds (like Zen, TM etc) and in almost all cases an increase in the alpha waves occurs during meditation.
Theta: 4-8 hz
Theta waves are often associated with deep states of meditation, peak spiritual experiences, and higher states of consciousness. Theta waves are associated with drowsiness or arousal in adults and older children. Young children are in theta most of the time.
Some people consider the theta state to be synonymous with the subconscious mind wherein reside suppressed emotions as well as a storehouse of creativity. Theta is associated with REM (rapid eye movement) sleep where dreams occur.
Important points about Theta Waves
Subjects are easily awoken from this stage of sleep, and it has many interesting properties. For a brief time as we lie in bed at night, neither fully awake nor yet asleep, we pass through a twilight mental zone like a state of reverie. Many people associate this drowsy stage with hallucinatory images, more fleeting and disjointed than dreams, and compare it to the viewing of a speeded-up, jerky series of photographic slides. A host of artists and scientists have credited the imagery of this twilight state with creative solutions and inspiration for their work. This theta stage is also observed in people under hypnosis.
Delta: up to 4 hz
Delta waves occur in adults during deep, or “slow wave” sleep. It seems this state is needed by the brain because after a period of sleep deprivation, there’s usually a rebound of slow wave sleep. Alcohol interferes with delta wave sleep.
Delta is considered by some to be the bridge to what Carl Jung described as the “collective unconscious.” Babies are in delta much of the time. For some reason adult females have been shown to have more delta wave activity. This is true not just in humans but in most mammals.
Important points about Delta Waves
Meditative states associated with the increased presence of delta waves seem to occur mostly in very experienced practitioners, possibly because entering a delta state and maintaining consciousness at the same time is
tremendously difficult. Also associated with the state of Samadhi, the deepest state in meditation as appeared in ancient Indian Yoga text.
Beyond the Basic Brain Waves
Mu 8–13 Hz used in Autism Therapy
The Mu wave is a brain frequency which has been observed and studied since the 1930′s. Mu waves are in the range of 8-13 Hz and arise from large groups of neurons in the brain.
Recently Mu brain waves have been associated with the “mirror neuron” system that activates when we watch another person’s activity. Because mu brain waves may play a role in our ability to understand and imitate others’ behavior, enhancing mu wave activity via neurofeedback is being studied as a therapy for autism. Early results are promising.
Gamma waves 25 to 100 Hz
Neurologists have also described a Gamma brainwave that’s thought to be involved with our sense of conscious awareness. Gamma waves range in frequency from 25 to 100 Hz though usually they are around 40 Hz. Studies of Tibetan Buddhist monks have shown a correlation between gamma waves and transcendental states of consciousness, but not all neuroscientists are convinced.
Important points about Gamma Waves
There is no such thing as a “gamma state” of mind. Gamma waves largely play a supporting and important role in the brain. From an EEG point of view, they are present mostly while a subject is awake, but they will always be supported by other waves in the beta, alpha, theta, or delta ranges. They have been noted during Buddhist meditation of compassion & music listening experiments.