In the 1980s, a researcher in Japan, Tsuyoshi Inouye described how light stimulation creates synchronization of brain hemispheres. Since then, other researchers have detailed the positive effects of hemispheric synchronization including a 1984 study by researcher Dr. Gene W. Brockopp stating that hemispheric synchronization resulted in improved intellectual functioning as well as improvements in long-term memory, and these effects are cumulative over time.
Research suggests the negative effects of stress on the body seem to be exaggerated in people who are inactive, a phenomenon called”stress-induced/exercise deficient” phenotype. Because we react to stress by experiencing changes in our neuro-endocrine systems, regular exercise is protective because it regulates various metabolic and psychological processes in the body, including reinforcing our natural circadian rhythms, sleep/wake cycles, moods and blood sugar levels.
Gamma brainwaves possess the highest frequency we know of. In this state, our brainwaves are so harmonious that many people report feeling elevated states of consciousness, even spiritual experiences. This frequency is often experienced by monks, nuns, yogis, and experienced meditators. Gamma frequencies also enhance memory, awareness, and mental processing.
Each of us is unique, and what works well for me might be totally useless to you. Generically speaking, there are three types of meditation techniques. There are techniques that take your awareness outwards, techniques that take your awareness inwards, and techniques that do a little of both. People with exceptionally busy minds tend to do better with techniques that take awareness outwards since their minds naturally head that direction anyway. People with more contemplative natures tend to do better with techniques that take you inwards. The combination techniques are a “maybe” for just about anyone, but are usually best used when a person has some experience with meditation under their belt.
Our brainwave states are natural. Guiding the brain into those states intentionally by using entrainment is just another way of experiencing those same natural states. Nothing “unnatural” is produced by the brain as a result of using entrainment. The only thing that is different is that when using entrainment we often go into the experience with either general expectations, or a well defined laundry list of specific expectations that we associate with entrainment. We have no such list going throughout our normal day when we’re not using entrainment.
If anybody would like to look over the scientific evidence concerning brainwave entrainment and isochronic tones, I’ve done a lot of research over the years which I’ve collected at the PubMed website of NCBI – a branch of the National Institute of Health – that provides access to a large library of medical journal articles. I’ve made my list public so you can look through the journal articles that were published concerning this topic. Here’s the link: Most of the collection only gives access to abstracts or summaries unless you’re at some kind of educational institution that has a subscription to the particular journal that article is in, but I actually find abstracts really helpful. So have at it, read away. And if your psychiatrist/therapist thinks you’re nuts for feeling better after listening to isochronic tones, just whip out your 82-page collection of scientific journal abstracts written by her peers and give it to her to read. 🙂
15. Melville GW, Chang D, Colagiuri B, Marshall PW, Cheema BC. Fifteen minutes of chair-based yoga postures or guided meditation performed in the office can elicit a relaxation response. Evid Based Complement Alternat Med [Internet]. 2012 [cited 2012 June 27]; Available from: doi:10.1155/2012/501986.

There are many advantages and disadvantages with binaural beats. One of the major advantages is hemispheric synchronization. Since both hemispheres are required to create the beat within the brain, this method is an excellent way to create greater harmony between areas of the mind typically functioning independently. Binaural beats are also known to have effective hypnotic and relaxing effects.
The immobilization response. If you’ve experienced some type of trauma and tend to “freeze” or become “stuck” under stress, your challenge is to first rouse your nervous system to a fight or flight response (above) so you can employ the applicable stress relief techniques. To do this, choose physical activity that engages both your arms and legs, such as running, dancing, or tai chi, and perform it mindfully, focusing on the sensations in your limbs as you move.
Beta: These brainwaves are associated with high levels of alertness and arousal. When beta brainwave patterns dominate, we’re primed to focus and concentrate, to make decisions and think analytically. When you’re analyzing an issue at work, you’re probably in a beta-dominant state. Beta waves are fast, with a higher frequency (between 15-40 hertz). At the higher levels of this range, beta waves are associated with anxiety.
Binaural beats, or binaural tones, are auditory processing artifacts (apparent sounds) resulting from the stimulation of the ears with two different sound frequencies. In fact, when two different vibrations are delivered to the brain separately through each ear, using stereo headphones, the two hemispheres of the brain function together to “hear” and perceive not the external sound signals, but a third phantom signal. This resulting signal, discovered in 1839 by Heinrich Wilhelm Dove, is called “binaural beat”. The effect on the brain waves depends on the difference of each tone. For example, if a sound frequency of 300 Hz is played in the left ear and 307 Hz in the right one, then the binaural beat would have a frequency of 7 Hz (“frequency following response”) which corresponds to the Alpha brain state, generally associated with relaxation, visualization and creativity. The beating tone is perceived as if the two tones mixed naturally, out of the brain. For the binaural beat effect to occur, the difference between the two frequencies must be small (less than or equal to 30 Hz), otherwise, the two tones will be heard separately, and no beat will be perceived.
Isochronic tones work just the same in delta as they do in alpha, theta and beta and they are widely used in the brainwave entrainment community to help people sleep. Like you, I’ve also seen some websites saying they don’t work in delta, but it’s a bit like the game of Chinese Whispers, where someone makes a comment and then after it gets passed around and shared a lot the message gets distorted and appears to be a fact. I don’t know of any scientific reason why they wouldn’t work in delta. I remember some people talking about this on a brainwave entrainment forum many years ago. They were saying they found isochronic tones a bit too abrupt for using to help them sleep and they preferred binaural beats, as they thought they were a more soothing sound. That was just a personal preference shared by a couple of prominent forum members at the time and some people then took that as a fact for everyone. That’s where I think that belief originated from.
The functional role of neural oscillations is still not fully understood;[6] however they have been shown to correlate with emotional responses, motor control, and a number of cognitive functions including information transfer, perception, and memory.[7][8][9] Specifically, neural oscillations, in particular theta activity, are extensively linked to memory function, and coupling between theta and gamma activity is considered to be vital for memory functions, including episodic memory.[10][11][12]