There are four measured Brain Wave states that we know of: Beta, Alpha, Theta & Delta. Some researchers claim that their is also fifth state, Gamma.
Brain waves are the electrical frequencies in the brain associated with various states of cortical arousal (thinking, learning, relaxing, recuperating etc.). Brain waves are measured in terms of Hertz (Hz).
For more information on Alpha, Beta, Theta & Delta waves ... visit Decoding Brain Waves
