First discovered by biophysicist Gerald Oster at Mount Sinai Hospital in New York City, Brainwave Therapy sends pure, precisely tuned sound waves of different frequencies to your brain via stereo headphones. In his EEG research, Oster discovered that when different vibrations, or sound frequencies, are delivered to the brain separately through each ear (as with stereo headphones), the two hemispheres of the brain function together to "hear" not the external sound signals, but a third phantom signal. This signal is called a binaural beat, and it pulses at the exact mathematical difference between the two actual tones. For example, a signal of 100 Hz delivered to the left ear, and a signal of 107 Hz delivered to the right creates a binaural beat of 7 Hz that in this case falls into the Alpha range
Other entrainment methods sometimes used include autopan modulation that moves sound in an 180º arc to create a desired tone. Harmonic box entrainment, invented by James Mann, uses a layering of binaural and monaural tones that alternate between ears, requiring headphones. Sound modulation and filtering, amplitude modulation, and pitch panning use diverse sounds to create rhythmic pulses matched to the desired brainwave frequency. 
Because EquiSync®'s audio-based brainwave entrainment technology guides your brainwaves into various states of meditation, it helps to understand how alpha, theta, and delta waves contribute to your state of consciousness. The two charts on this page illustrate the basic benefits of each brainwave state as well as the targeting of the EquiSync programs 1, 2, & 3.
it says the following: “Running a delta sleep session throughout the night is not recommended as it can interrupt the normal sleep cycle”. I’ve been looping pure delta isochronic tones for about 5 days now, and have had quality sleep. Should I continue looping delta or should I let the videos play out without looping them? Will it will harm my health to do loop delta while I sleep?
With brain wave entrainment technology, changing brain wave states is an instantaneous and effortless process. The 'periodic stimulus' can be sound, vibrations and/or light. We have found that we get the best results with blinking lights which are experienced through closed eyelids. This is only problematic for people with existing diagnosis of photo-induced epilepsy, as blinking lights can induce a seizure in them. The programs are enhanced with Deepak Chopra doing the narration along with holographic sound effects and original music composed and performed by Rudy Tanzi.

The most common way to use a brainwave entrainment is for a short-term benefit, to help guide your brain into a particular mental state at the time you need it.  In a similar way to how you might take a sleeping pill before bed to help you get to sleep, or maybe drink some coffee or an energy drink to help wake you up and give you a boost of energy.

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.
The good news is there are loads of guided meditations which will not only take you into theta brain waves, but will make you feel good about yourself at the unconscious level too. These are some of my favourite types of brainwave entrainment - and you can get them on topics such as money, confidence, creativity, success, relationships, weight loss, smoking and more.
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.