Brain Waves
The brain contains some 100 billion neurons. These neurons operate by generating and passing electrical signals, or electrical activity that can be detected and recorded outside the brain. Recording of brain activity is done by a device called an electroencephalogram (EEG). It is the recording of this pattern that is popularly referred to as "brain waves." Brain waves appear as irregular, somewhat repetitive waveforms, and are a mixture of many frequencies. The frequencies have a variety of names, divided and labeled according to the speeds at which they flow from the brain.
Brain waves are the voltage patterns generated by the brain. The waves are measured in individual units called Hertz, meaning the number of times a repetitive event occurs per second. Named after physicist Heinrich Hertz (1857-94), they used to be called “cycles per second." One Hertz is the individual wave that one sees on either a screen or a print out of recorded brain waves.
The slowest brain waves, called Delta waves, are measured at .5 to 3 Hertz per second, and are associated with sleep. The next measurable rate of brain waves is 3 to 7 Hertz per second; these are called Theta waves. Theta waves are associated with imagery and suggestibility. They occur during the dream state, and also during hypnosis. Following Theta is the term for relaxed awareness, at 7 to 13 hertz per second. These are called Alpha waves. Within the next state, the Low Beta, 13 to 18 hertz per second, is the Sensory Motor Rhythm state, at 12 – 15 Hertz per second. Low Beta is characterized by alert awareness, and the Sensory Motor Rhythm state is the range at which one usually operates machinery. Following the Low Beta is the High Beta, which entails a rate of 18 to 30 Hertz and is characterized by being tense and super alert. The final state that has been named is the Gamma state at 30 Hertz per second and up, which entails being hyper alert and possibly creative in specific ways.
Experimentation and published research on the altering of brain activity has been going on for decades. A vast amount of applicable data has been collected by researchers and scientists concerning the manipulation and influencing of brain waves and states of consciousness. One effect discovered by German scientists in the 1930’s is called the Ganzfield effect. It is an effect in which the eyes are exposed to a totally uniform visual field, with no edges, color changes, or movement. This effect can be achieved by looking up at the sky on a clear, cloudless day, or with very specially constructed illuminated glasses. It affects the circuitry in the brain, which normally is constantly scanning the visual field for edges and movement. The eye responds primarily to changes, and with visual sensations shut off and the brain finding absolutely nothing, the subject cannot tell if his eyes are open or closed. This is an example of an altered state of consciousness resulting from the shift in brain waves to the Theta state.
The effects of flickering light stimulation have been known for centuries. Ancient shamans used flickering lights to achieve a trance state, a key component in the development of the spiritual practices of a wide variety of ancient cultures. In the literature of the common era, Ptolemy noted around 200 A.D. that the flickering of sunlight seen through the spokes of a spinning wheel could cause patterns and colors to appear to the observer, producing a feeling of lightheadedness and euphoria. The onset of modern times, (1940's and 50's) brought the research of neuroscientist W. Gray Walter. Walter used a strobe light to create flickering light stimulation, noting that the brain wave pattern of the cortex—just the area associated with vision—was changed.