I'd second this to some extent. I've been using f.lux (and now the default Night Shift in macOS/iOS) for years. I don't remember if my eyes hurt normally, but

I'd second this to some extent. I've been using f.lux (and now the default Night Shift in macOS/iOS) for years. I don't remember if my eyes hurt normally, but I can say that if I now turn it off at night my eyes hurt, I strain and get a headache after a while. It may just be because I'm used to the colours now. I don't think it has helped my sleep patterns much, though, it's only reduced eye straight for me. Using a computer (or a phone) beyond a certain time usually kills my sleep regardless.