Well, for one thing they (at least in ASUS's case) appear to do the opposite of Night Light / flux by subtracting the blue channel rather than increasing the re

Well, for one thing they (at least in ASUS's case) appear to do the opposite of Night Light / flux by subtracting the blue channel rather than increasing the red channel. This means at first the image looks a tad green/yellow-er, but you get used to it much more than Night Light's red tint. I've had it for a year now, mostly on the highest level (certified as "70% blue light reduction") and I still sometimes check that it's on. (But once you see the onscreen UI in a blue-ish white it's very obvious) My eyes also get a lot less fatigued with it on compared to OS features/flux, even after tuning my monitor & room brightness accordingly with a colorimeter. A lot of it might come down to certification and blue light reduction methods at the monitor level. In ASUS's case they claim to be certified by TUV Rheinland[1]. [1] https://www.asus.com/Microsite/display/eye_care_technology/ https://www.asus.com/Microsite/display/eye_care_technology/