I can offer a hypothetical--however do not know know practical it will turn out to be. There is a fair amonut of bad science on this topic on you tube. The gamma wave frequency is associated with attentional focus and arguably a unified sense of self. If it could be entrained it should lead to a meditative focus-like exceptionally well-trained meditators. Some but not all studies on meditating Buddhist monks suggest this is so. Does this really and more generally occur--I will say there is nothing lost in trying--we all go into a 40Hz range on occasion without ill effect-- but I would not put confidence in the purported methods out there at present. Good luck.
- Added the ability to create a playlist of your own iTunes library music and use it as background. The behavior of the app with iTunes music is used instead of, or combined with our included ambience, is slightly different so please review the help. Notably, unlike our included ambience which can be played at a volume below the device volume, iTunes audio can only be played at the device volume. So when in iTunes mode the Ambience volume slider disappears.
Theta waves have another interesting characteristic. The Earth has a measurable resonance of 7.83 hertz known as the Schumann resonance. Because the Schumann resonance is a constant background frequency surrounding all life, it may play a special role in biological activity. The Schumann resonance frequency falls within the range of theta brainwaves and may have something to do with why these brainwave frequencies are so powerful. 
Cvetkovic D, Simpson D, Cosic I (2006). “Influence of sinusoidally modulated visual stimuli at extremely low frequency range on the human EEG activity“. Conference proceedings : … Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 1: 1311 – 4. doi:10.1109

This music encourages a state of delta relaxation. Delta brainwaves are most prevalent during deep, dreamless sleep. The delta state is a mostly unconscious state that is essential to one’s physical, emotional, psychological and spiritual wellbeing. People who are able to achieve a state of delta relaxation through meditation will sometimes describe spiritual encounters and out of body experiences. The delta state is perfect for inducing profound spiritual experiences, healing and deep subconscious repatterning. Delta frequency brainwave entrainment music is also a fantastic cure for insomnia.
When making an educated decision on what product is best for you, it is important to have a general understanding of how the technology works, and what the benefits are of visiting the specific brainwave states.  Please click the link to visit a more detailed article –  How Does Brainwave Entrainment  Work, and the benefits of Alpha, Theta, Delta, and Gamma brainwaves.

So you see, it’s all about where your personal journey is taking you, and what direction of evolution you are wanting to explore.  The purpose of this site is to assist you in making an educated decision about what product is right for you, and to ensure that you are only recommended a high-quality product that will provide you with powerful and noticeable results.  The great news is that many of the benefits of using Brainwave Entrainment (improved sleep patterns, release of anti-aging hormones, whole-brain functioning, etc.) are simply side-effects of using any type of brainwave entrainment audio.
3) Theta waves – these waves exist between 4 and 7 Hz. This state is commonly referred to as the dream or “twilight” state. Theta is associated with learning, memory, REM sleep and dreaming. Memory development is also enhanced while in this state. When in a theta brainwave state, memory is improved (especially long-term memory), and access to unconscious material, insights and creative ideas is increased.
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.
Thanks for making Brain Wave the Top-Selling Brainwave Entrainment App in the App Store! * This update includes support for iOS 6, an optimized UI for iPhone 5, and a new ambient forest background. The app is universal, so you get it across all your devices with one app! Includes optimized UIs for iPhone/iPod Touch, iPhone 5, iPad and support for landscape and portrait orientations.
In BrainAscend, each brainwave frequency is stimulated for several minutes before progressing deeper.  Much like a staircase type of progression, but with small and smooth steps. This is the most effetive way and also stimulates the release of "feel good" brain chemicals such as serotonin which makes you feel happy. This chart shows the range that each level covers as well as the whole program.
To get a full answer you should really get in touch with the owner of the app, because it does really depend on how their track is constructed and how they intend it to work. I have one 50-minute sleep track which takes you down into delta (http://www.mindamend.com/shop/sleeping-and-dreaming/sleep-induction-isochronic-tones/) and that is designed to just get you to sleep, so you just let play until the end. If you played that track on repeat it might make you jump and wake you up, as the track begins at a higher frequency. I have another 8-hour sleep track which is meant to be played all throughout the night (http://www.mindamend.com/shop/sleeping-and-dreaming/deep-sleep-8-hour-sleep-cycle/). So it does depend on the individual track you are using.
I first became aware of brainwave meditation programs  and brain waves when researching alternative methods for treating the bipolar disorder I had been unsuccessfully living with my entire adult life. I eventually learned a method of releasing difficult emotions on the spot, which I then practiced extensively, and consequently found it easier and even desirable to meditate for fairly lengthy periods of time. Though I took up meditation as a serious daily practice and experienced many undeniable benefits, I nonetheless intermittently experienced life-debilitating bouts of mania and severe depression, often resulting in chaotic mixed states and an inability to maintain daily social functions. During these times, it became nearly impossible to sit in meditation.
Research shows that parts of the brain and eventually large areas of the brain begin to resonate sympathetically with this "phantom" binaural beat. This is known as the Frequency Following Response. Subsequent research determined that a binaural beat frequencies drive brain activity into specific brain states. Thus, effortlessly and naturally, your brain activity slides into rhythm with this binaural beat, becoming organized and coherent. Within minutes, the sound frequencies start to balance the left and right hemispheres of your brain – creating a remarkable state called hemispheric synchronization and driving the electrical activity of your brain into powerful states, normally unattainable. Flashes of creative insight, euphoria and a deep sense of calm is often accompanied by this extraordinary brain state.
Hi EJ, at the moment, there hasn’t been any research to give an indication of how long you should or shouldn’t listen for. Over time, I’ve seen people use my tracks for longer and longer. I started off providing 30-minute study tracks, but through demand, I extended them to 3-hours. I know from the many thousands of comments I’ve had on YouTube that a large number of people play those 3-hour tracks on repeat, or listen to different ones, one after the other throughout the day. I’ve also seen apps where you can play tracks like mine on continuous repeat. So it’s common for people to listen to them all day while they are studying.

In 1984 medical researcher Dr. Gene W. Brockopp published a paper making several conclusions of audio and visual entrainment (AVE). Such conclusions were that hemispheric synchronization caused by AVE is related to increased intellectual functioning, practiced use of AVE overtime leads to a cumulative effect, and AVE may result in the recovery of early childhood experiences.
Brainwaves, or neural oscillations, share the fundamental constituents with acoustic and optical waves, including frequency, amplitude and periodicity. Consequently, Huygens' discovery precipitated inquiry[citation needed] into whether or not the synchronous electrical activity of cortical neural ensembles might not only alter in response to external acoustic or optical stimuli but also entrain or synchronize their frequency to that of a specific stimulus.[16][17][18][19]