Thank you for the info. I must add that the Yoga Nidra state is the state in which a person can be in Delta but fully conscious. I did experience this state accidentally 3x in 2yrs after discovering Swami Rama’s teachings about the state&1 of the techniques for it(only 4 seems to exist & are practiced in monasteries at the time,according to him. He was the yogi who 1st demonstrated the 4 states,fully aware of himself & his surroundings, under lab conditions).
Hemispheric synchronization: Whether it’s optimal or suboptimal to operate in a state of hemispheric synchronization remains unknown. Some speculate there are numerous benefits of brain waves operating in “sync” as a result of entrainment. There may be an increased communication between the right and left hemisphere of the brain – which could improve certain functions. However, it is also important to realize that increased hemispheric synchronization may not be as beneficial as many have speculated.

The mechanism for this is that when your eyes or ears are exposed to a particular frequency of pulses or beats, the thalamus first distributes this information to the entire brain, including the visual and cerebral cortex where neural activity begins to synchronize to the incoming frequency, producing hemispheric synchronization and a balance of brainwave activity across the brain.
I also believe that the dangers of brainwave entrainment should be further explored as well. There are relatively vague benefits, but it remains unclear as to whether entraining certain frequencies may be detrimental to performance or induce harm. Despite the fact that brainwave entrainment has existed for a long term, it remains an understudied niche in neuroscience.

AVE is capable of producing situationally appropriate brain wave frequencies through the process of entrainment (the tendency of physiological processes to mirror environmental stimuli). AVE also increases cerebral blood flow (blood flow in the brain) and increases the metabolization of glucose in the brain for improved functioning of the neurons. The combined outcome of these processes is improved mental performance. It is an effective, inexpensive alternative therapy for many disorders such as anxiety, Attention Deficit Disorder (ADD), Seasonal Affective Disorder (SAD), PTSD, Fibromyalgia and chronic pain. Our AVE devices are also used successfully to boost physical performance for athletes, academic performance for students and cognitive performance for seniors.
In the past few issues of the Advocate Voice Newsletter and the Fibromyalgia & Chronic Pain LIFE magazine, we have offered ideas about  several forms of cognitive behavior and mindfulness information.  In the chronic pain community these techniques combined with other therapies, including medications and alternative modalities, can help people sleep, function, relieve stress from pain and improve their quality of life.  This month’s app, Brain Wave, 30 Binaural Programs, is another tool to help introduce the idea of using your mind to help control pain and relieve stress.
The various mental states of the individual are thought to take place across a varied range of frequencies, or brainwaves. By encouraging the frequency following process, entrainment is able to create positive change in the brain, through matching carefully-selected frequencies of light and/or sound. The stimulus enables the individual to access a different state of consciousness, which can be useful for a number of benefits including relaxation, anxiety management, stress reduction and more.
A common element in recordings incorporating alpha and theta frequencies is a steady but barely perceptible rhythm of the frequencies themselves. This subtle and calming pulse mixes with sounds of gentle breezes, distant bird songs, and the slow progression of deep synth notes. Underneath this, below the audible sounds at sub 16 hertz levels, other frequencies intermingle, deepening the merging of conscious and unconscious mind.

This is good to understand because this is another area where people can make huge promises that may or may not be true. Even in this realm, there is a level of practicality that can be followed. Even meditating at the rate of a super-human monk is not going to “magically solve all your problems”. This technology cannot pick negative beliefs out of your head and implant positive ones just by influencing your brainwaves. It cannot just make you a different person.

Our brains follow cues from outside stimuli, and brainwaves mimic the pulse rates of the sounds we expose it to. So, by creating tracks that pulse sound waves at a desired frequency, we can effectively coax our brain into that state. In layman's terms; by listening to some strange sounding brainwave frequency audios, we can literally slip our brain into a state of feeling calm, alert, focused, energized... and the list goes on. Pretty cool, right!?
I wouldn’t personally recommend listening to delta wave frequencies for depression, so I’m not sure who advised you to do that? People with depression usually have a higher ratio of theta and delta wave activity, so I would normally recommend listening to high alpha wave and low beta wave frequencies, to help balance things. I have some 10Hz alpha tracks for serotonin release, which you can try for free on my YouTube channel here: I also recommend you give these SMR (low beta wave) tracks a try: I hope that helps.
Chronic fatigue: Subjective improvements in energy level may be reported by those who increase stimulatory beta and gamma waves. Fast waves tend to be associated with higher levels of arousal. Low arousal is associated with chronic fatigue and may be exacerbated by slow brain waves (e.g. theta and delta). As of now there aren’t any studies that have analyzed various protocols for their effect on a person’s energy or arousal.
Brainwave entrainment can help you with this in a few different ways. First it has a tendency to help you relax very deeply. Just the act of relaxing daily will help to alleviate this stress and allow the body and brain to recoup. It also will stimulate the brain and body to produce more serotonin, dopamine, and melatonin, which will also help to improve your mood and keep you relaxed. But the greater benefit that comes from regular use of this technology is in its ability to enhance your awareness and perception. It can stimulate your brain and mind to have greater insights, greater flexibility and creativity in the decisions you make as you move through life, and this gives you a more resourceful means of finding your peace and resolving the problems and challenges you face in your life.
If brainwave entrainment leaves you with unwanted side-effects (see below) or discomfort, you’re probably encouraging a range of brainwaves that are already excessive in some area of your brain. The way around this is to get a brain map to see what your brain’s strengths and weaknesses are, and see what (if any) brainwaves could use some encouragement.