Throughout the natural universe, there is a tendency toward rhythmic alignment or entrainment. Striking an “A” tuning fork will cause other nearby “A” tuning forks to vibrate. Women who live in close quarters, such as college dorms, tend to synchronize their menstrual cycles over the course of time. Grandfather clocks placed in the same room will tend to swing their pendulums in sync with the dominant or largest pendulum. Crowds of people at a concert will tend to clap in unison to the beat of the music. Persons sitting close together will begin to synchronize their breathing rhythms. These are all examples of entrainment— a powerful and universal natural phenomenon.
he human brain also tends to follow rhythm. The electrical activity (EEG) of our brain is rhythmic and seen as “brain waves”. When we listen to music with a fast beat, our brain waves tend to speed up. When we listen to music with a slow beat, our brain waves slow down. It is also known that flashing lights can affect brain waves. Flashing a light steadily into the eye will stimulate the brain and cause brain waves to entrain to the same frequency as the flashing light— that is, the amplitude of the brain waves at the same frequency as the flashing light will increase. Flashing the light faster will increase the amplitude of higher frequency or faster brain waves, whereas flashing the light slower will increase the amplitude of lower frequency or slower brain waves. This frequency following effect of brain waves in response to rhythmic stimulation is called “brain wave entrainment” (BWE).
Neurotherapists capitalize on this natural phenomenon because of its potential to alter brain wave amplitudes and patterns.
Audio-visual entrainment (AVE) refers to the use of flashing lights and rhythmic tones to purposefully entrain brain waves toward some desired rhythm or frequency. By stimulating the brain with flashing lights in special eye glasses and pulsing tones through head-phones it is possible to shift the frequency of the dominant brain waves either higher or lower and thereby change brain function.
What does AVE do?
Our brains produce four basic brainwave states: beta, alpha, theta and delta. A healthy brain will produce the appropriate brainwaves for a given situation. For example, when a person is sleeping soundly, the brain normally shows a great deal of very low frequency delta (1-4 Hz) activity and relatively small amounts of higher frequency theta, alpha and beta waves. On the other hand, during the waking state, the normal brain shows predominantly alpha and beta activity with less theta and very little delta activity.
Similarly, when a normal adult sits quietly in an awake but relaxed state or meditates, the brain shows a great increase in alpha (8-12 Hz) activity and some theta (4-7 Hz) activity but relatively little delta or beta activity. On the other hand, a person who is alert and mentally active will show increased amounts of higher frequency beta activity (13-30 Hz).
Due to stress, neurotransmitter imbalances, genetic factors, brain injury, or other trauma, people may produce too much or too little of certain brain waves for certain activities. For example, many people who have trouble falling asleep and/or experience frequent waking during the night, do not produce enough very low frequency delta (1-4 Hz) brain waves at bedtime and, when they do manage to fall asleep, will experience frequent bursts of higher frequency alpha (8-12 Hz) activity which will bring them up into wakefulness.
Another common problem is seen when the brain chronically produces too much high beta (20-30 Hz) activity and the person feels constantly anxious, “wired” and hypervigilant and simply cannot relax.
Another problem is seen in persons with Attention-Deficit Disorder, these people frequently have brains that produce too much slow wave theta (4-8 Hz) activity, especially in the frontal areas of the brain, when they try to do such mental tasks as reading.
All of these problems can be helped with AVE. For the person who cannot sleep at night, AVE can be used to stimulate the brain at very low delta frequencies to enhance production of delta waves in the brain. For the person with anxiety and hypervigilance, AVE can be used to stimulate an increase in theta and alpha wave activity which will result in feelings of relaxation. Similarly, attention-deficit can be treated by stimulating an increase brain activity in the lower beta range of 12-16 Hz, which is associated with relaxed attentiveness.
Mood disorders such as depression and seasonal affective disorder may improve with AVE stimulation in the low and middle beta range (12-20 Hz).
What problems can be treated with AVE?
There is a rapidly growing clinical and research literature supporting the use of AVE in the treatment of the following disorders…
· Seasonal Affective Disorder
· Attention Deficit Disorder
· Posttraumatc Stress Disorder
AVE is especially effective for most people as a means of inducing deep relaxation and relieving stress.
AVE can be a beneficial “stand-alone” treatment for many disorders and can produce changes in many conditions in only a few treatment sessions. AVE is also frequently used by therapists in conjunction with other EEG neurotherapies such as EEG biofeedback and/or Cranial Electrotherapy Stimulation (CES), or with psychotherapy.
What does AVE feel like?
AVE in the clinic usually involves having the patient sit in a comfortable chair in quiet room with their eyes closed and wearing a set of special eyeglasses and a set of headphones. The eyeglasses have little LED lights built into them and these lights gently flash against the closed eye lid and are perceived as a diffuse pattern of flickering light. The headphones will emit a pulsating tone that will be synchronized with the flashing lights. The intensity of the lights and the volume of the tones are adjusted to be completely comfortable.
Treatment sessions usually last about 30 minutes.
Most patients are left feeling relaxed and alert after an AVE session— in what psychologists call an “alpha state”. Positive changes are usually felt within one to three sessions and include improvements in mental clarity, uplifted mood, increased mental alertness and energy, increased feelings of calm.
What are the adverse effects of AVE?
While AVE has a proven track record of safety, especially in comparison to alternative pharmaceutical treatments for the same conditions, there is a small risk of seizure for persons who are epileptic or have a history of seizures. The prevalence of photosensitive epilepsy is about 1 in 4000 children and young adults, lesser in older adults and slightly higher in females. Some patients find the light stimulation, even when set very low, to be irritating. In some cases, headaches, vertigo or feelings of anxiety may be triggered. Such adverse reactions are always temporary and resolve quickly when the stimulation is stopped.
What is the evidence for the effectiveness of AVE?
Research studies of AVE go back as far as the 1950s but it is really only in the last two decades that AVE has developed into a clinical technique for treating brain-based problems. While there continues to be a serious lack of large sample, controlled research studies on AVE, there are literally hundreds of clinical reports in the professional literature showing AVE to hold significant promise in the treatment of anxiety and depression, seasonal affective disorder, insomnia, and attention-deficit disorder. There is also good support for the use of AVE as a stress management and relaxation tool as well as for pain relief. Clinically, AVE has been used quite successfully to induce deep relaxation and help in hypnosis. There is evidence that AVE can be used to “sharpen” cognitive functioning in the elderly who are showing early signs of age-related dementia.
Treatment of Depression: A recent study by David Cantor and Emily Stevens at the Psychological Sciences Institute in Duluth, Georgia examined the effects of 4 weeks of daily 14 Hz audio-visual EEG entrainment on 16 depressed subjects. They reported that 4 weeks of AVE treatment was associated with a significant reduction in depressive symptoms as well as EEG changes over time in cortical regions associated with mood regulation. They concluded that AVE therapy may be a viable nonmedication therapeutic intervention for individuals with mild to moderate depression.