Brainwaves and Meditation Machines
In the 1940s researcher Gray Walter discovered that brainwave activity tends to mirror flickering light, particularly in the alpha and theta frequencies. This effect has become known as the frequency-following effect. A familiar example is the tendency to slip into a relaxed or dream-like state while gazing into a fire-the flicker rate of which happens to average in the alpha/theta range.
More recently, sound has been shown to produce similar results, particularly pulsed sound and binaural beats. This last effect, binaural, results when one ear hears a pure tone of a slightly differing pitch than the other ear. The brain then actually synthesizes the difference between the two and then falls into step with this pleasant, gently pulsing rhythm.
Meditation Machines make use of this research by combining light and sound frequencies to automatically lead brainwave activity into alpha and theta states making them particularly effective tools for relaxation and meditation.
The four types of brain waves in more detail
Beta waves (15-30 oscillations (or waves) per second (Hz)). This is the brain rhythm in the normal wakeful state associated with thinking, conscious problem solving and active attention directed towards the outer world. You are most likely in the "beta state" while you are reading this.
Alpha waves (9-14 Hz). When you are truly relaxed, your brain activity slows from the rapid patterns of beta into the more gentle waves of alpha. Fresh creative energy begins to flow, fears vanish and you experience a liberating sense of peace and well-being. The "alpha state" is where meditation starts and you begin to access the wealth of creativity that lies just below our conscious awareness. It is the gateway that leads into deeper states of consciousness.
Theta waves (4-8 Hz). Going deeper into relaxation and meditation, you enter the "theta state" where brain activity slows almost to the point of sleep. Theta brings forward heightened receptivity, flashes of dreamlike imagery, inspiration, and,sometimes, your long-forgotten memories. It can also give you a sensation of "floating".
Theta is one of the more elusive and extraordinary realms we can explore. It is also known as the twilight state which we normally only experience fleetingly as we rise up out of the depths of delta upon waking, or drifting off to sleep. In theta, we are in a waking dream, and we are receptive to information beyond our normal conscious awareness. Some people believe that theta meditation awakens intuition and other extrasensory perception skills.
Delta waves (1-3 Hz). This slowest of brainwave activity is found during deep, dreamless sleep. It is also sometimes found in very experienced meditators.
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In the living brain, millions of nerve cells communicate with each other by emitting tiny electrical impulses. This activity can be registered as oscillations (popularly called brainwaves) by placing electrodes on the scalp, amplifying the signals and displaying them on a computer monitor. This method of measuring is called electroencephalo-graphy (EEG).
Alpha, Beta, Theta and Delta
Brainwave activity tends to fall into four groups: beta, alpha, theta and delta. These categories are associated with the rapidity of oscillation (frequency) of brainwaves. As it turns out, certain patterns of brainwave activity are also associated with specific mental states.
During unconscious states, (e.g. deep sleep), the slow delta waves are dominant, whereas it is the high-frequency beta waves that are prevalent during concious, wakeful activity. Of particular interest to us, though, are the alpha and theta waves.
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