This sounds like an excellent idea to me. I use redshift and have various sleep troubles that often keep me up when it is dark. I've tried manually shutting it off when I'm awake at night, but I find that now that I am used to the shifting my eyes do not appreciate a bright screen in a dimly lit room. I sometimes use brighter ambient lighting but haven't found it makes much difference for me (quite likely related to my specific issues). I think in general keeping both the screen relative to the ambient light and ambient light relative to sleep schedule is important. Of course, I'm one of those paranoid types who disable the webcam in the bios unless expecting to use it so that wouldn't help me specifically, but ambient light sensors sound like something every computer should have IMO.