We are all unique and herbs can work differently for different people. The usage instructions on the label are written to be applicable to a general population. However, that doesn't mean they are optimum for you and the discomforts you are experiencing (small vs. large body types for example). "As needed" means you should take the amount listed at a needed frequency until you feel the desired effect (paying attention to any maximum or frequency limitations listed).
While visual entrainment is more powerful than audio alone for inducing desired brainwave states, more caution is needed when using visual methods. Between 0.3 and 3 percent of the population is susceptible to having seizures from flickering light stimulation, and for other people, flickering visual stimuli simply makes them uncomfortable. People with epilepsy have a greater chance of having a seizure from exposure to flickering light stimulation.
Participants in the included studies were children and adults, either healthy or with conditions such as learning disabilities, attention deficit hyperactivity disorder, migraine, stress, anxiety and myofascial pain. Interventions included single, alternating, ascending or descending frequencies of photic or auditory stimulation or audiovisual entrainment selected either by the participant or by the investigator. Nearly half the studies used single sessions and the rest used multiple sessions ranging from nine to 100. Length of session varied from 0.5 seconds to 60 minutes. Frequency of session varied from twice daily to weekly. Outcomes reported in the review included cognition (including verbal skills, performance skills, attention, memory and overall intelligence/achievement), short- and long-term stress, pain, headache/migraine, mood, behavioural problems and premenstrual syndrome (PMS).
Given that brainwaves control and connect such a vast range of human experience from thought to feelings to actions, it is easy to see how the deliberate control of brainwaves can affect mood, behaviors, motivation, and even physical health. Brainwave entrainment is a safe, simple, and scientifically proven method for quickly guiding the brain into a beneficial brainwave frequency to facilitate healthy sleep, lower stress, heal emotional problems, and improve physical health.
“In order to get into a flow state, you have to calm a part of the brain, the posterior cingulate cortex, which is the source of what brain scientists call the default state, which is the non-focused state,” says Harris. “At any rate, it turns out that Holosync [binaural beats], when you listen to it, [calms that part of the brain] and so does traditional meditation. It’s just Holosync does it faster and more easily and more effortlessly. It turns down the posterior cingulate cortex and it enhances the other part of the brain that, when it’s enhanced, you can easily go into a flow state.”

Delta brainwaves have the slowest frequencies, ranging between 0.1 and 4 hertz, and these are the brainwave states associated with deep sleep, trance states, and unconsciousness. Few people can remain awake during delta brainwaves states, although this state is recorded in awake infants between ages of three months and one year and also in babies just before birth. Delta waves are also linked with increased production of HGH, DHEA, and the neuro-transmitter serotonin.

That is generally where the science ends and the pseudoscience begins. A number of companies and individuals have then extrapolated from the phenomenon of entrainment to claim that altering the brain waves changes the actual functioning of the brain. There is no theoretical or empirical basis for this, however. Entrainment is a temporary effect on the synchronization of neuronal firing – it does not improve or increase brain functioning, it does not change the hardwiring, nor does it cure any neurological disorder. There is no compelling evidence for any effect beyond the period of entrainment itself.
Binaural beats were the first method discovered for brainwave entrainment and works by delivering tones of different audible frequencies to the two ears with the difference in frequency between the two tones being the frequency of entrainment. The difference in frequency between the two tones must be less than 30 hertz, and this resulting frequency is called a beat or the target frequency, and it is processed in a brain region called the olivary body. When listening to such tones with stereo headphones, the two hemispheres of the brain become synchronized at the target frequency.
♥ I found the Binaural Beat Machine to be my #1 focus tool. I have ADD/ADHD and am too easily distracted when I really want to focus. I turn on the binaural beats using the 16b preset for focus and turn down the volume so it's just barely present to my ear. I couple it with some classical music and am able to focus on what I want for extended periods. This literally has changed my life. Thank you!!

Both brainwave entrainment and neurofeedback deal with brainwaves, but the similarity stops there. Entrainment pushes your whole brain into a pre-determined state, while neurofeedback teaches you how to move specific parts of your brain on your own. It is the differeence between forcing the brain into a given position, and skills building so you can move it there yourself. 
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