...  While entrainment by binaural auditory beats in the alpha frequency has also been shown to enhance creativity, cognition, memory, and an improvement in intelligence tests and achievement tests in learning disabled boys.  The gamma-band activity has been shown to involve in a variety of functions such as attention, memory, and consciousness. Current literature suggests that entrainment by gamma beats promotes cognitive flexibility, modulates visual attention, and enhances creativity. ...
In the 1980s, a researcher in Japan, Tsuyoshi Inouye described how light stimulation creates synchronization of brain hemispheres. Since then, other researchers have detailed the positive effects of hemispheric synchronization including a 1984 study by researcher Dr. Gene W. Brockopp stating that hemispheric synchronization resulted in improved intellectual functioning as well as improvements in long-term memory, and these effects are cumulative over time.
And so we (not too surprisingly) begin to experience “symptoms” or “signs” of something that we do not ordinarily experience. Immediately, we associate these with the entrainment or the meditation. We wonder if this is something real or imagined so we often start asking others if they have experienced the same or similar things. We seek validation that our practices are producing tangible effects on us.
Turns out, science says there is something to needing “fresh air”—even opening a window can help get more oxygen to your brain, soothing stress. “We live so much of our lives indoors, that when stress hits, one of my go-to techniques is to get outside or open a window,” Dr. Serani says. “Taking in a nice deep breath of crisp fresh air can immediately shift your neurochemistry.” If you’re overwhelmed with work, it can seem hard to take a break; but a quick step outside is even recommended by the American Psychological Association. When you come back, you’ll be recharged and ready to take on the challenge.
Theta: This brainwave pattern is associated with deep relaxation and with some stages of sleep, including the lighter stages of non-REM (NREM) sleep. REM sleep itself is mostly composed of beta wave and other activity that’s similar to an alert, waking brain. Deep meditation produces theta waves, which are slower and lower frequency (between 5-8 hertz) than Alpha waves. That murky barrier between sleep and wakefulness, when you’re drifting in and out of sleep, and your thoughts feel dreamlike and difficult to remember? That’s a theta-dominant state of consciousness.
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.