A very intriguing theory why something as mundane as hyperventilating yields a certain desired altered state of consciousness is because the vasoconstriction is affecting first and foremost the more modern and (for survival) less essential parts of our brain tasked with analytic and rational thinking - which happens to be exactly what one wants to curb for a more direct access to and experience of emotional states.
It should also be noted that while all sorts of breathing techniques have been repeatedly rediscovered for thousands of years it was the psychiatrist Stanislav Grof who prominently introduced Holotropic Breathwork to the West as a means of alternative to LSD after it had been banned in the US.