Guessing these are surfacing due to the recent Radiolab podcast "The Spark of Life": https://radiolab.org/podcast/the-spark-of-life

> in the spectral range of 200–1000 nm

That's UV, visible and near IR. We know that 100-600 nm (infrared EDIT: UV) light "can carry out photostimulation and photobiomodulation effects particularly benefiting neural stimulation, wound healing, and cancer treatment" [1]. I'm curious what could be producing UV and visible light.

Does light production tend to hang out around any particular organs or organelles? If stress causes it, I'd hypothesise it's metabolic or signalling related.

[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC5505738/

I would assume respiratory complexes I and III in mitochondria. Both used highly reduced states to create the gradient to pump protons, and electron leakage is inevitable.

This likely then leads to redox transitions in quinones, flavins, metal centres, leaving them in unstable excited states. When they relax, the excess energy has to go somewhere - usually thermal energy, but just occasionally, a photon.

This would also tally with anaesthetics and injury having an effect, as both effect mitochondrial function - and of course when you’re dead, so are your mitochondria.

> 100-600 nm (infrared) light

Ultraviolet, you mean.

> I'm curious what could be producing UV and visible light.

There is tons of chemoluminescent stuff in a live being. As my spectroscopist friend says, everything luminesces at some point.

The brain is electro-chemical, hold all sorts of minuscule charges… I guess once the process for keeping that all going comes to abrupt halt, electric potentials change which would take into account some electromagnetic field :shrugs: