Google have added a night-reading mode to their Play Books app on Android (and iOS), called 'Night Light'. When enabled, the feature gradually filters blue light from your screen, replacing it with a warm, amber light as the sun sets. Night Light automatically adapts to the amount of natural sunlight outside based on the time of day at your location. This should reduce strain on your eyes, particularly before you go to sleep, so it's definitely a good thing. The problem? We actually REALLY want a proper e-ink reader.