Your brain cells reset their sodium & potassium ratios when the brain is in Theta state. The sodium & potassium levels are involved in osmosis which is the chemical process that transports chemicals into and out of your brain cells. After an extended period in the Beta state the ratio between potassium and sodium is out of balance. This the main cause of what is known as "mental fatigue". A brief period in Theta (about 5 - 15min) can restore the ratio to normal resulting in mental refreshment.  
I would like to share with you my experience after using EquiSync for three weeks. First of all, I am so amazed how fast I can put myself in a meditation state. During meditation, I feel some kind of a sensation I could not explain. I feel the rain dropping on my face and sometimes my legs. I feel the breeze of a tropical weather as if I was in the forest. I always sleep for a very short time at night and I have a very high sense of smell all my life. Using equisync I still sleep less, but am more relaxed when I wake up. During meditation, I can also smell the forest as if I am in the forest.
Brainwave entrainment is a field of study and endeavor founded in the same physiological and psychological processes that make music, drumming, and chanting so powerful as methods for transforming the mind and spirit and aiding in healing of the body. These processes involve how the electrical energy in our brains synchronizes with sounds and visual stimuli, producing a particular brainwave frequency and its associated mental states. 
♥ I'm a tired law student always looking for a study boost. I like to put on the Alpha waves and mix this with classical music for research and writing. The "beats" help to drive the music and add a feeling of focus and energy even during slower/softer passages. If you get the levels matched properly, you never even hear them. Throw in a cup of coffee and you'll be ready to save the world. Cheers!

First of all, thank you for a most remarkable achievement. I have tried products in the past that purported to synchronize meditation-level brain waves — usually overlain by sappy new-age music composed by non-composers — and was invariably disappointed. However, I have been using your Equisync II and Equisync III recordings for a few weeks now and the results are truly astonishing and live up to the claims on your website.
Resonant entrainment of oscillating systems is a well-understood principle within the physical sciences. If a tuning fork designed to produce a frequency of 440 Hz is struck (causing it to oscillate) and then brought into the vicinity of another 440 Hz tuning fork, the second tuning fork will begin to oscillate. The first tuning fork is said to have entrained the second or caused it to resonate. The physics of entrainment apply to bio-systems as well. Of interest here are the electromagnetic brain waves. The electrochemical activity of the brain results in the production of electromagnetic wave forms which can be objectively measured with sensitive equipment. Brain waves change frequencies based on neural activity within the brain. Because neural activity is electrochemical, brain function can be modified through the introduction of specific chemicals (drugs), by altering the brain's electromagnetic environment through induction, or through resonant entrainment techniques.
Newberg won't go so far, but other proponents of the new brain science do. Michael Persinger, a professor of neuroscience at Laurentian University in Sudbury, Ontario, has been conducting experiments that fit a set of magnets to a helmet-like device. Persinger runs what amounts to a weak electromagnetic signal around the skulls of volunteers. Four in five people, he said, report a "mystical experience, the feeling that there is a sentient being or entity standing behind or near" them. Some weep, some feel God has touched them, others become frightened and talk of demons and evil spirits. "That's in the laboratory," said Persinger. "They know they are in the laboratory. Can you imagine what would happen if that happened late at night in a pew or mosque or synagogue?" His research, said Persinger, showed that "religion is a property of the brain, only the brain and has little to do with what's out there." Those who believe the new science disproves the existence of God say they are holding up a mirror to society about the destructive power of religion. They say that religious wars, fanaticism and intolerance spring from dogmatic beliefs that particular gods and faiths are unique, rather than facets of universal brain chemistry.

The aim of this study is to identify tendencies in the effectiveness of relaxing audio stimuli that could be verified through further focused experiments. A series of brainwave entrainment (BWE) techniques for inducing relaxation will be presented consisting of different binaural phenomena (BP). The BP will derive from the binaural sine wave beat, widely acknowledged in rhythmic BWE... [Show full abstract]
Belief and faith, argue believers, are larger than the sum of their brain parts: "The brain is the hardware through which religion is experienced," said Daniel Batson, a University of Kansas psychologist who studies the effect of religion on people. "To say the brain produces religion is like saying a piano produces music." At the Fuller Theological Seminary's school of psychology, Warren Brown, a cognitive neuropsychologist, said, "Sitting where I'm sitting and dealing with experts in theology and Christian religious practice, I just look at what these people know about religiousness and think they are not very sophisticated. They are sophisticated neuroscientists, but they are not scholars in the area of what is involved in various forms of religiousness."

Most wisdom traditions have employed methods that allow the subjects' brain waves to slow down such as meditation, [Hindu] kirtan, [Gregorian, Menzuma or Sufi] chanting, Hebrew davening, Native American drum circles and rain chants, Tibetan prayer bowls, and whirling dervishes and African trance dancing. The rhythm of these wisdom tradition technologies actually slows people's brain waves from their normal busy brain frequency we call Beta (13-30 cycles per second or Hz), to Alpha (8-13Hz) -- meditation, Theta (4-8Hz) -- deep relaxation and dreaming, and Delta (.5-4Hz) -- slow wave or dreamless sleep.

Brainwave entrainment is a method to alter the frequency of your brainwaves by listening to audible tones containing the desired frequency. So if you want to sleep, you would listen to audio that begins at your current frequency and slowly descends to a delta frequency. By introducing these new lower frequencies, your mind begins to lower its own brainwaves to match this new frequency.
So, in summary, binaural beats certainly do not work the way the sellers claim, but there's no reason to think they're any less effective than any other music track you might listen to that effects you in a way you like. If they make you sleepy (like they all do for me), use them to go to sleep. If they relax you or get you amped, use them for that. But don't expect them to be any more effective than regular music. If someone you know claims that they are, put them to the test, and bust the myth.
After nearly two years of daily use of this brainwave meditation and brainwave technology, I began to enjoy a quality of life–without medication–that once seemed quite impossible for me. I do not say this lightly. Not only did I enjoy a fulfilling life, I also experienced what seemed like significant development in self-concept, values, interpersonal skills, creativity, accelerated learning, intuition, ability to handle stressful situations, self-esteem, sense of purpose, and social awareness.
Today we're going to put on our headphones, kick back in the beanbag, and get mellow to the soothing sounds of the latest digital drug: binaural beats. These computer generated sound files are said to massage your brain and produce all sorts of effects, everything from psychedelic experiences to behavior modification. Let's point our skeptical eye at the science of binaural beats, and especially at some of the claims made for them.