When landing at night on most planes they say that due to safety regulations the lights will be dimmed and if you want to continue reading you can use your overhead lamp(it could be that this only happens in Europe I am not sure). I wonder what is the reason for this? What safety does dimming the lights add?
Dimming the lights allows your eyes to pre-adjust to darkness, so that you're not suddenly blinded if something happens and the power goes out, and you are trying to find the doors in darkness or smoke. In addition, the emergency path-lighting and signs will also be more visible. And it makes it easier to see outside, which helps you to maintain at least a basic sense of orientation - i.e. which way is up. Raising your window shade during takeoff and landing is also part of the same strategy.