About

Brainwave entrainment is any practice that aims to cause brainwave frequencies to fall into step with a periodic stimulus having a frequency corresponding to the intended brain-state (for example, to induce sleep), usually attempted with the use of specialized software. It purportedly depends upon a "frequency following" response on the assumption that the human brain has a tendency to change its dominant EEG frequency towards the frequency of a dominant external stimulus. Such a stimulus may be aural, as in the case of binaural or monaural beats and isochronic tones, photic (visual), as with a dreamachine, a combination of the two with a mind machine, or electromagnetic radiation.

Hemispheric synchronization, a potential and generally desired result of brainwave entrainment, refers to a state when the brainwave pattern of the right and left hemispheres become alike. A person with similar activity in both hemispheres is alleged (typically by companies trying to sell a product) to be happier, more optimistic, more emotionally stable and less prone to mental illness. Increased levels of synchronization are found naturally in people who meditate regularly and people who are very content with their lives in general.