i don't think there are much but i made my research a decade ago after realizing i was having a good time with my smartphone compared to my e-reader

[1] suggests that LCD even increases processing speed compared to e-ink

[0] https://pubmed.ncbi.nlm.nih.gov/22762257/

[1] https://bop.unibe.ch/JEMR/article/view/2338/3534

there's a study from Havard concluding "e-ink is 3 times better for eye health than LCD" but it feels rather dubious from the claims (blue light stressing more the retina... like i couldn't use a glass or apply a filter on my screen), light intensity (again...), in-vitro study and who funded the study (a great e-ink screen producer) -> https://sid.onlinelibrary.wiley.com/doi/10.1002/jsid.1191

i probably read hundred books since i sold my e-reader and moved to my smartphone. i really like having a single device. battery is fine. physical books with images still rocks but maybe becuse i don't have a tablet :)

I've spent thousands of hours (I think) reading on a phone. I even prefer it over a physical book because it doesn't have that annoying crease and it doesn't spoil the story by telling me how far along in the book I am.