Interesting about CO2 and the divers’ breathing, thanks.
About 2 years ago I did and extensive Pub Med journal article review on the “Neuroscience of Fasting and Starvation.”
I primarily did it to understand the spiritual aspects of fasting. The result, I still need to test in the lab, but basically the ketone process provides a better fuel source for the brain allowing or facilitating the action potential firing rate to reach the gamma frequencies necessary for the mystical experience.
Perception of reality changes with brain wave frequency.