Those seeking within spiritual domains but still based in scientism, often look with hope to the direction of biophotons. The main reason is probably the fact, that photons are quanta of electromagnetic field, and this stuff is less material. Thus, from a certain perspective, there might be a hope for an explanation of human biofield, aura, light being, or subtle bodies (e.g. astral).
The scientific community from which this approach was derived was formed around prof. Popp in Germany in the 1990s. Their attempts aimed to describe health and disease through biophotons at both experimental and theoretical levels. However, this community exaggerated a bit their desire for wholistic and holistic understanding and slipped from a strictly scientific path into too many speculations without proper evidence. Since then, the term biophotons has developed a sort of esoteric connotation while its use was spread into new age communities.
That’s why a more suitable term biological autoluminescence was introduced for scientific studies by our close collaborator Michal Cifra in 2014 [1]. Since then, our collaboration in this field continues, however, with primary research not so holistic as can be seen in our latest paper. Still, there is a biomedical potential in this topic, as previous works showed, for example, that cancer cells produce an increased intensity of biological autoluminescence.
Final verdict: Relevant research area, within natural and medical sciences, not in spirituality or esoterism.
References:
[1] Cifra, M. and Pospíšil, P.: Ultra-weak photon emission from biological samples: Definition, mechanisms, properties, detection and applications, Journal of Photochemistry and Photobiology B: Biology 139, 2-10, 2014