*The last link (the Life mastery thing) has got some science and explanation behind this g-breath and it's working. You need to register and take the course (watch videos i.e) on 'Breath Mastery'. All that is told there is from a whole different point of view and may be difficult to relate to; but the end point is that they're talking about generating brainwaves using breathing techniques, mainly gamma that will be 'converted' to other brainwaves.
*Another thing that I might add is that I did this g-breath thing, and felt some really feel-good kind of sensations in my head (the light headed feeling that they call), and gamma is supposed to produce such kind of effect with increased alertness, so perhaps, this does indeed produce gamma waves.
*About Chakras, I have read that Chakra meditation strengthens the dream body thus make it easy for us to achieve lucid dreams. Aso, I have read that Chakra meditation generates theta-gamma waves. I am currently researching about this and shall update here if I find out anything concrete.
Treatise on Lucid Dreaming