why do airlines turn off the cabin lights at night during takeoff and landing?

1) They dim the lights to help your eyes adjust to the outside light, so if anything happens and it goes dark, you're not suddenly blinded while dashing for the exits. 2) Lowering the lights makes the emergency path/exit lights more visible, as these might be the only lights you see in an emergency. Letting your eyes adjust will help you see this path with more clarity. 3) You are also asked to raise your shade so that in the event of an accident you can see through the window to help you remain oriented (which way is up, etc.). Because of this, it lets you see what hazards there are outside the plane (fires, debris and such), which would be very important to know during an evacuation. Most importantly, it serves as a way to let light into the cabin and make it easier for rescuers to see inside.  more