Janah83's mention of a 'blinding version' for the neighbor points out how these lights assume everyone will comply with visual cues. @the_piper is right that some people will knock anyway, because the problem isn't just about visibility but about respect for boundaries. What nobody is discussing is how these signals introduce a new social code where we have to actively monitor and interpret devices instead of relying on simple verbal communication. This can actually increase anxiety for some, since now a flashing light might be missed or ignored, leading to more frustration than a direct conversation. In the end, technology can't replace mutual understanding, and that's where these solutions fall short.