Airlines dim cabin lights during takeoff and landing to enhance passenger safety by allowing their eyes to adjust to potential darkness. This adjustment period is crucial for improving visibility should an emergency evacuation become necessary. When lights are bright, the pupils constrict, and it takes time for them to dilate and adapt to lower light conditions. By dimming the lights before the aircraft even begins its descent or acceleration, passengers' eyes are already prepared to see better in the dark, enabling them to navigate exits and surroundings more effectively during a critical situation. This practice is a proactive safety measure that leverages human physiology. During daylight hours, the cabin lights are dimmed to a level that allows for this pre-adaptation. At night, the cabin is already darker, so the dimming is less pronounced but still serves to ensure eyes are accustomed to the ambient light. The goal is to minimize the time it takes for passengers to orient themselves and move towards safety if an emergency occurs. This preparation is vital as takeoff and landing are statistically the most critical phases of flight, where the majority of aviation accidents occur. Furthermore, the dimming of cabin lights also aids the flight crew. As the cabin lights are lowered, the crew's ability to see outside the aircraft is also enhanced. This allows them to better spot potential hazards on the runway or surrounding areas during critical phases of flight. The reduced glare from cabin lights also helps the pilots in the cockpit maintain better situational awareness, especially during nighttime operations. The entire procedure is a coordinated effort to maximize safety margins for everyone on board. In essence, the seemingly minor act of dimming cabin lights is a well-established safety protocol designed to leverage the natural capabilities of the human eye. It ensures that passengers and crew are as prepared as possible to react swiftly and effectively in the unlikely event of an emergency during the most vulnerable stages of a flight. This measure, alongside numerous other safety procedures, contributes to the overall high safety record of commercial aviation.