Just as stress can increase the risk for chronic diseases and other health problems, dealing with chronic conditions and poor health can increase the amount of stress one experiences. Stress also influences behaviors that affect health. Diet choices, sleep habits, and drug use are behaviors that are often negatively affected by stress (3). The APA’s 2011 survey showed that 39% percent of respondents reported overeating or eating unhealthy food because of stress, and 29% reported skipping a meal (3). In addition, 44% reported lying awake at night because of stress (3). On a positive note, 47% of respondents reported walking or exercise as a way of managing stress (3).
“One of the best ways to explain how brainwave entrainment works is by observing the effect of a tuning fork on a guitar string,” says Naik. “Hit a tuning fork tuned to a particular sound frequency, such as the note C, and hold it close to the strings of a guitar. You will notice that the C string on the guitar starts to vibrate because it has entrained on to the same frequency of the tuning fork.”

In the average person, the activity of one brain hemisphere is dominant over the other, called brain lateralization. This hemispheric imbalance leads us to experience the world in a black and white way, perceiving separation over connectedness. When brainwave entrainment is used to synchronize brainwave activity in both hemispheres simultaneously, a person can more easily integrate information from all parts of the brain and solve problems with greater intelligence and sensitivity.

Many people experienced in using alpha brainwave entrainment report that the state of mind associated with alpha waves is a time when they feel most consciously connected to their subconscious mind. The intense experience of hypnagogic sleep, reported by some people as a feeling of being awake and asleep at the same time, is also associated with alpha brainwaves.
Theta brainwaves are next highest in frequency above delta and are especially important for many people using brainwave entrainment and meditation because theta waves are at a threshold, forming a link between wakefulness and the subconscious mind. Theta waves bridge between our awake self and the creative and insightful understandings from below our conscious awareness, and while they are not common in awake adults, they are normative for children under 13 years old. 
There are five main categories of brainwave frequencies: Gamma (40Hz+), Beta (13 – 40Hz), Alpha (7 – 13Hz), Theta (4 – 7Hz), and Delta (<4Hz). Each category is associated with a different state of mind; so, for example, when you’re in a peak state of performance, your brain produces Alpha Waves, and when you’re in a deep sleep, your brain produces Delta Waves.
In physics, entrainment is the process of two oscillating systems coming to assume the same periodic rhythm, such as is observed when two clocks slowly synchronize their ticking and tick together in harmony after some time. Pendulums also achieve this same synchronicity when swinging in close proximity to one another, a phenomenon first observed and written about in 1665 by Christiaan Huygens, a Dutch scientist.

Binaural beats must be listened to using headphones. You definitely should not use them while driving or operating heavy machinery as you will be in an altered state of mind. Brainwave entrainment is a form of meditation and designed to be very passive, in fact, all you need to do is sit back, put on your headphones and let the technology do the work for you. It is best to find a session that you find soothing to listen to, as binaural beats on their own are a very strange sound that can be disturbing to some listeners. This was actually what inspired me to invent Trypnaural as a way for brainwave entrainment to be more bearable to listen to for long periods of time.
Alpha is the next level down, between 8Hz - 12Hz, corresponding to being awake but deeply relaxed. It can be a little confusing that Alpha is lower than Beta, but it is named that way because Alpha was the first brainwave "discovered" (identified) by Hans Berger in 1929. Meditating in this state is very relaxing and most people find it very easy to become entrained in this frequency.
The activity of neurons generate electric currents; and the synchronous action of neural ensembles in the cerebral cortex, comprising large numbers of neurons, produce macroscopic oscillations. These phenomena can be monitored and graphically documented by an electroencephalogram (EEG). The electroencephalographic representations of those oscillations are typically denoted by the term 'brainwaves' in common parlance.[4][5]