Synchronized brain waves have long been associated with meditative and hypnogogic states, and audio with embedded binaural beats has the ability to induce and improve such states of consciousness. The reason for this is physiological. Each ear is "hardwired" (so to speak) to both hemispheres of the brain (Rosenzweig, 1961). Each hemisphere has its own olivary nucleus (sound-processing center) which receives signals from each ear. In keeping with this physiological structure, when a binaural beat is perceived there are actually two standing waves of equal amplitude and frequency present, one in each hemisphere. So, there are two separate standing waves entraining portions of each hemisphere to the same frequency. The binaural beats appear to contribute to the hemispheric synchronization evidenced in meditative and hypnogogic states of consciousness. Brain function is also enhanced through the increase of cross-collosal communication between the left and right hemispheres of the brain.
A simple spinal twist can help you get a better night's sleep. It alleviates tension that's built up in your lower back throughout the day. Sitting on your bed with legs crossed, place your right hand down on the bed behind you and rest your left hand on your right knee. Sit up straight and inhale for four to eight counts, lengthening your spine as you breathe. On your exhale, begin to twist toward your right hand (don't strain your neck). Hold this position for four more full breaths, lengthening your spine on the inhales and deepening your twist on the exhales, if it feels comfortable. Repeat yoga asanas on opposite side. (These stress-reducing yoga poses also help calm anxiety.)
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.
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.