Seeing brilliant lights during near-death experiences may arise from a surge of bioluminescent biophotons in the brain when blood flow returns after oxygen deprivation. The authors propose that reperfusion triggers an overproduction of free radicals and excited molecules, leading to a transient increase in biophoton emission within retinotopic visual areas. If this emission exceeds a threshold, the brain interprets the intrinsic photons as external light, creating the perception of brilliant lights. The article reviews experimental studies that support this concept and links the idea to phosphenes, dream-like imagery during REM sleep, and self-consciousness possibly involving low-energy quantum entanglements. It is presented as a discussion piece, not a definitive explanation.
A complex hypothesis proposes that serotonergic psychedelics act on gut microbes, prompting host enterochromaffin cells to temporarily increase production of 5-HT (serotonin). This 5-HT is taken up and distributed by platelets, potentially acting as a hormone-like signal that influences membrane permeability in organs and the brain. Elevated plasma 5-HT may transiently increase blood-brain barrier permeability, allowing 5-HT to enter the central nervous system via volume transmission. There, gut-derived 5-HT could modulate excitatory and inhibitory neurotransmission, causing network disintegration. This transient neural disruption may allow patients access to suppressed fear information and enable an emotional reset, with the amygdala playing a key role.