That is a general assumption people make but there isn’t really much science to back it up. What we do know though is that isochronic tones are ineffective below 4hz, and possibly a bit higher. So for theta and delta entrainment you are best off with binaural beats. In my experience binaural beats will be very effective all the way up to around 40hz.
Unlike many traditional therapies for dealing with stress, anxiety, depression or cognitive impairment, entrainment does not require a focused effort from the person having the therapy, as the brain instinctively follows the frequency. This makes it a much more effective therapy for managing some of these challenging conditions, by automatically inducing a sense of relaxation and a reduction in negative physical and emotional patterns.
The specific benefits and claims from this technology are often disputed and considered scientifically questionable. One problem is that there are few experiments that have utilized brainwave entrainment for the purpose of treating a specific psychological ailment (e.g. insomnia). And the experiments that have been conducted are largely backed by corporations that sell the software; hence it could be speculated that there are conflicts of interest.
2. Dimensional sound insures that the brain perceives the entrainment as more realistic, which produces more natural and thorough engagement in each meditation. Not only does this create more pronounced effects and an intensified response, but it also avoids the fatigue generated by overuse of standard sound – as can occur with extended use of other audios.
There's no doubt that brainwave entrainment audio is a great technology for anyone who is interested in encouraging altered states of consciousness and it certainly can help people to reach deeper states of relaxation than they might normally have access to. I myself will often listen to brainwave entrainment music in order to enhance my practice of meditation. But let’s keep a balanced perspective, put all the marketing hype to one side for a moment and acknowledge that there is no brainwave entrainment technology in this world that can make you meditate like a Zen monk “at the touch of a button”, despite what some might like you to believe. The mind is NOT a machine. It moves through various states of consciousness in an organic way and at a natural pace. We certainly can guide and accelerate that process with the use of brainwave entrainment audio, but we cannot control it with the same sort of specificity and immediacy as you might control the speed of the car you drive.
Insomnia and PTSD for most of my life are real bears that I wrestle with every night. A brain neural-therapist (for lack of a better description) said that this kind of sound recording may help. It is not music. When I remember to play the disc, I fall asleep within the first 5-8 minutes. One day I played the disc while cleaning and I was very surprised to hear how much of the recording I never recall hearing before. That's why I know how long it takes to fall asleep.
Research: the authors stated that qualitative electroencephalogram signatures needed to be developed for different disorders and tested using standard validated methods of psychological assessment. Larger RCTs were needed with clear inclusion criteria for participants. The RCTs should measure qualitative EEG, hormone levels and the time of day of the intervention. Interventions protocols should be clearly defined and the relationship between session frequency/ duration and outcomes should be explored. More studies of auditory stimulation were needed, as well as studies comparing different types of stimulation, monaural, binaural and isochronic beats and use of white noise versus music.
The main gist of brainwave entrainment audios, without getting too technical here, is that they effortlessly guide one’s brain (when listened to with stereo headphones) into a specifically targeted state, as designated by the creator of the audio. They are able to alter your brainwave states through the use of specific audio frequencies, and specific beats-the most common of which being binaural beats (though there are other types of beats being used as well).  When one frequency is played into one ear- let’s say 1115 Hz- and a slightly different frequency is played into the other-say 1125 Hz- the brain is forced to reconcile the two, and creates its own “phantom” frequency that is the difference between the two- in this case 10 Hz.  Not only does this allow the brain to be led into specific brainwave states, but it also allows the two hemispheres of the brain to synchronize with each other, stimulating and promoting whole-brain functioning.
Hi Amandeep. I am so sorry to hear you are having these troubles. I am not familiar with Marisa Peers materials, so I cannot comment on this, but I can tell you we have never had an experience like this reported from using the audios we offer on this site. I would cease any and all hypnosis or brainwave entrainment audios, and contact your doctor. The issues you are mentioning sound like they could be a physical issue that may be related to more than the audios you’ve listened to.

By the 1980s, entrainment technology had merged with advancements in microelectronics technology, making it possible to develop even more sophisticated audio and visual brainwave entrainment products for the marketplace. In the last two decades, a number of scientific studies have reported brainwave entrainment as an effective remedy for ADD, academic learning problems, and improving memory and cognition.

The training process allows you to consciously access deeper levels of your brain and consciousness. Your whole brain power and function expands. You become intuitive, relaxed yet focused, creative, your thoughts become clearer and information processing improves more and more. The left and right brain hemisphere synchronizes and you'll start using the full power of your left (analitycal - logical - Intelligence) and right (creativity - imagination - visualisation) hemispheres together. To say that this helps in all imaginable areas of your life is an understatement. You'll also begin to discover deeper realities beyond the physical. You become happier, more relaxed and balanced.
Depression: Currently there is no substantial evidence to support the idea that brainwave entrainment treats depression in adults. Some evidence goes as far as to suggest that the wrong entrainment protocol (e.g. slow wave stimulation) may actually increase certain measures of depression. Stimulation of delta and/or theta, will likely worsen the condition and alpha is unlikely to have an effect.
Regarding split hemisphere isochronic tones. Think of this as two separate isochronic tones tracks playing independently of each other, one playing in one ear and the other one in the opposite ear. Better still, imagine someone playing and recording a drum beat at a rate of 5 taps per second (5Hz – 5 cycles per second). Then a separate recording of a drum beat is made at a rate of 10 taps per second (10 Hz). You then make an audio track where the left ear/channel hears the 5 drum beats recording and the right ear/channel hears the 10 beat recording. With headphones on, each ear can only hear each respective drum beat and not the other. So you are hearing two different beat recordings at the same time, but it’s different in each ear. A split hemisphere isochronic tones track works just the same. You hear two beats at the same time, not two tones as with binaural beats that create a single beat, but two different speeds of beats in each ear. This is what enables you to stimulate and influence each side of the brain with a different frequency of beat. Binaural beats can only stimulate and influence a whole brain effect using a single beat.
What happens when you meditate using the Profound Meditation Program 3.0 is that instead of statically giving the nervous system the same level of juice every day, you consciously attune and intuitively adjust your nervous system and your energetic system’s unique stimulation recovery cycle. With PMP 3.0, you have a type of system with enough carrier frequency power and biofield amplitude to push your nervous system and your energetic system for a lifetime—and it is a system as dynamic as your growth and recovery cycles are. This system will enable you to push your spiritual development and growth much more quickly, recover much more quickly, and experience less overwhelm.

Stress: In one randomized controlled trial with 108 participants, a single session of alpha and delta stimulation resulted in significantly less anxiety in surgical patients. Another session of theta stimulation resulted in improvement in certain measures of stress. Stimulation with certain frequencies of alpha and beta were reported to provide the most significant benefit for those who are stressed.
Another small scale study with 30 children were entrained with a starting frequency of 14 Hz and ramped up to 40 Hz. Following the excitatory-based protocol, they were then given a protocol that started at 40 Hz and decreased to 14 Hz over 6 weeks. The results indicated that the children significantly improved in arithmetic abilities based on the WISC-III.
Alpha stimulation: Stimulation of alpha waves has been shown to provide stress-relief among employees, is able to provide pain relief, and improve measures of competence and recognition. If you have significant work-related stress, entraining certain alpha frequencies may help you decrease arousal and improve relaxation. Post-surgical stress doesn’t appear to benefit from alpha stimulation.

Gamma brainwaves occur during creative thinking and processing of memory and language and in many learning activities. These brainwaves are not present at all when a person is under anesthesia, but return as soon as the person becomes conscious again. Multiple scientific studies have shown gamma brainwave entrainment to be helpful for reducing distractibility, improving short-term memory, improving motor coordination, and relieving migraine headaches.
When you embark on this accelerated journey, more than ever you need to understand that brainwave entrainment is a powerful tool, but that your actions, thoughts, and how you use this powerful tool are still strong determining factors in how much you get out of the technology. It’s not just an easy way out. You are going to have to go through a growth and transformational process.
1. Compressed formats like MP3 do not retain the sound quality necessary for the brain to fully achieve brainwave synchronization – and are too inferior to effectively deliver even binaural beats downloads or isochronic tones properly, much less something as powerful as NeuralSync™. Our lossless audio entrains at the precise level guaranteed to induce the most potent response.
Mood: While brainwave entrainment may not be a great option for depression, particularly in the slower frequency ranges, beta entrainment may improve certain measures of mood. Additionally it is important to consider the fact that many people experience detrimental changes in mood as a result of heightened stress and anxiety. Since brainwave entrainment has been shown to improve stress and relaxation, overstressed individuals may experience a simultaneous mood improvement.
One of the more fascinating aspects of what brainwave entrainment does, long-term, is the growing of your mental threshold, and your self-awareness.  I have been a participant of the Holosync Solution for several years, and its maker, Bill Harris, has gone to great lengths to explain why this technology does this.  Much of his research is based on the concept of Entropy and Open Systems, (an idea that nominated its discoverer for a nobel prize).  The brain being an open system, and the technology being a specific type of entropy, this technology has been shown to help the brain reorganize itself at a “higher level” through the growth of new neural pathways. This basically means that 
Because the mind and body are a single system, changing our brainwaves and spending more time in harmonious, relaxed, and restorative mind-states also affects our physical health. Physical health then reinforces our mental-state, and a feedback loop of either positive or negative processes becomes established. Research studies have shown beneficial effects of using brainwave entrainment for treating migraine headaches, premenstrual syndrome, and for managing physical pain.

Entrainment is a physics principle in which one rhythmic system falls in synchrony with another rhythmic system. If you’ve ever found yourself moving your body to the beat of your favorite song, then you’ve experienced entrainment in its most basic form. Besides music, this principle can be found all around you, probably more than you realize. Here are a few examples:
Brain Sync audio programs deliver pure and precisely tuned sound frequencies to the brain to drive brain activity into high level states of mind. These are brain states known as Alpha for heightened creativity and deep relaxation; Beta for high focus and concentration; Theta for meditation, insight and memory; Delta for deep sleep and healing; and Gamma to increase cognition and improve IQ.
Anyone who has sought out different methods for enhancing cognitive ability will probably have come across a technique known as Brainwave Entrainment. However, it is a fairly niche area of brain training, meaning that this form of stimulation is often overlooked in favour of more mainstream methods. The following outlines what Brainwave Entrainment actually is, how it is used, and some of the benefits attributed to it.

Entrainment is a physics principle in which one rhythmic system falls in synchrony with another rhythmic system. If you’ve ever found yourself moving your body to the beat of your favorite song, then you’ve experienced entrainment in its most basic form. Besides music, this principle can be found all around you, probably more than you realize. Here are a few examples:

Slower still are theta waves. Theta is best known as the brain wave state of dreaming sleep, but it is also associated with a number of other beneficial states, including increased creativity, some kinds of superlearning, increased memory abilities, visionary experiences, and what are called integrative experiences (where we make broadly-based positive changes in the way we see ourselves, others, or certain life situations).
Also, don’t you think that the inherent hemispheric synchronization using binaural beats might be a positive benefit within itself? While it’s true that the huge majority of us use both sides of our brains most of the time, it’s also true that many of us are a bit polarized to one side or the other in general, or when doing a particular kind of activity or focus. I’ve found stimulating a more equally and consistently whole brain activity has it’s own benefits other than the entrainment aspect.
So using the example track above, the right ear is sent a 20Hz beat, compared to a 10Hz beat in the left ear.  As the right ear receives the higher frequency of beat, this works to increase the speed of the ‘left' brain hemisphere, which can be helpful for people with conditions like ADD, who are often found to have an abundance of slow wave activity in the left brain.