When stress overwhelms your nervous system, your body is flooded with chemicals that prepare you for “fight or flight.” This stress response can be lifesaving in emergency situations where you need to act quickly. But when it’s constantly activated by the stresses of everyday life, it can wear your body down and take a toll on your emotional and physical health.
I have seen 1.5Hz being linked to HGH, but also 4 or 5 other frequencies as well, so it’s difficult to know what may work if any. I haven’t seen any research relating to HGH and brainwave entrainment. It’s widely believed that 40Hz is the limit for achieving a brainwave entrainment effect, which is also where many believe the gamma frequency range begins. Once you get over 40Hz into gamma your brainwave activity isn’t likely to stay in sync with it. So from a brainwave entrainment perspective, I recommend high beta frequencies for increasing energy during workouts.
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Today, EEG machines are used for diagnosing epilepsy and sleep disorders, for determining dosages for anesthesia, and measuring the brain activity of people in comas or suffering from brain trauma. EEG machines also continue to play a role in researching and understanding brainwave entrainment and developing new and better methods for delivering the benefits of this form of brainwave modification. 
First of all, thank you for a most remarkable achievement. I have tried products in the past that purported to synchronize meditation-level brain waves — usually overlain by sappy new-age music composed by non-composers — and was invariably disappointed. However, I have been using your Equisync II and Equisync III recordings for a few weeks now and the results are truly astonishing and live up to the claims on your website.
Among the four dominant types of brainwaves, the Theta wave has earned the reputation of perhaps being the “most creative”. The dominant pattern when people are in the dream stages of their sleep, a person with increased Theta brainwaves during waking activity has a very high level of thinking and creativity. With a high amplitude and frequency of 4 Hz to 8 Hz, Theta waves are often dominant in the brain’s right hemisphere, which is also the hemisphere of highly-creative people. Here are some of the benefits you might enjoy with an increased Theta brainwave production:
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.

Long-distance running, biking, cross-country skiing, and other outdoor activities provide a change of scenery and a dose of fresh air, both of which can help clear your mind, Plante says. Also, outdoor settings such as mountains, a biking trail, or a neighborhood park are pleasant places to spend time in. Beautiful settings, especially in spring and fall, can lift your mood and shake up your workout routine.
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. 
The phenomena of brainwave entrainment was first described in the scientific literature in 1973 by Gerald Oster in results published in an article in Scientific American entitled, “Auditory Beats in the Brain”. He showed that a specific brainwave could be induced when a person heard two separate, but closely related, sound frequencies, one in each ear. He discovered that when the frequencies heard by each ear differed by about 10 hertz, the brainwave pattern of the person hearing the sound would synchronize to the difference between the two frequencies. For example, if the person heard a 410 hertz sound in one ear and a 400 hertz sound in the other ear, their brainwaves would stabilize at the difference between the two, or 10 hertz. This technique is called binaural beats, and it is a fundamental principle of brainwave entrainment methods.
I’ve been using equisync first thing in the morning after I get up, and listen to all three tracks in a row. I again listen to all three tracks in the late afternoon. If I don’t have that much time available, I will start on Track 2 or 3, as necessary. I have really started to focus on my breathing, and notice the difference – I finish the session in a DEEPLY relaxed state.

Another consideration of stress is whether it is acute or chronic. “Acute stress” is what an individual experiences at the time the stressor is encountered (4). The stress response is activated, and the body returns to homeostasis once the challenge of the stressor is removed or the person successfully manages the situation. For example, an individual on the way to an important meeting gets into a traffic jam and realizes she is going to be late; the stress response starts. When she calls her boss and learns that she can conference into the meeting while on the road, the stress response subsides with the resolution of the situation. When an individual experiences acute stress on a consistent basis, such as with overcommitting at work or constant worrying, it is referred to as “acute episodic stress” (4). Individuals who experience acute episodic stress often show signs and symptoms of stress (Table 1) that can negatively impact physical and psychological health. These individuals can learn how to change behaviors and manage their stress to prevent these consequences.

This session uses a proven technique for inducing deep relaxation, playing one frequency for two minutes, then alternating to a second after a 30-second ramp, then reversing the process. The first half of the session switches between a serotonin-boosting 10Hz and the grounding and rejuvenating 7.83Hz Schumann resonance. The second half of the session goes even deeper, alternating between the relaxing 7.83Hz and 6.3Hz, a frequency associated with releasing anger and irritability. The session ends on a chilled out 10Hz.