There’s A Reason They Turn Off The Lights
As the plane prepares for takeoff or for its descent, the lights in the cabin will get shut off. This is never really explained and there’s not much to think of it since the lights get turned back on just a few minutes later.
But there’s actually a good reason for this. Takeoff and landing are the most problematic stages of a flight. The lights get turned off so that everyone’s eyes can adjust to the light in the event of an emergency. This can help people orient themselves with the space easily if they needed to take action.