The Potentially Scary Reason Why Airplanes Dim the Lights Before Takeoff

No, it doesn’t mean naptime.

If you thought pilots dimmed the cabin lights before takeoff to give you some shuteye, think again. Believe it or not, the dim lighting could actually help save your life in case of a plane emergency.

The dimmed lights before taking off the runway and landing are a flight precaution used to help passengers’ eyes adjust quicker during an emergency evacuation. “Going from a brightly lit cabin environment to one that’s pitch black would require some time for our eyes to focus and see the evacuation slide,” Alice Theriault, service director for Air Canada wrote in a press statement. “Since we need to have all the seconds on our side in the event of an emergency, dimming the lights is one of many steps we take to ensure the safety of our customers.”

Those weird speckles your eyes see as your sight adjusts to a dark place after being in a light place is called dark adaptation. If you see drifting gray spots in a lighted room, that’s something different called floaters, and here’s what you can do about them. Dark adaptation usually takes our eyes about 20 to 30 minutes to see optimally in a dark room. The brighter the lights, the longer it takes for our eyes to adjust, which is why dimming the plane lights could shorten your “dark adaptation” time since you haven’t been sitting under fluorescent bulbs all flight.

Not only do dimmer lights add valuable time to the evacuation process, it eases the strain on your eyes if you need to look outside, locate signs, or see the emergency lighting along the aisle. “It helps you remain oriented,” Patrick Smith, an airline pilot and author of Cockpit Confidential told The Telegraph. “It also makes it easier for flight attendants to assess any exterior hazards, such as fire or debris, that might interfere with an evacuation.” So next time a pilot dims the lights, just know it’s for your safety, even though it creates a soothing ambience for your takeoff into the sky.

Here’s some more airplane trivia you’ve always been curious about.

Ashley Lewis
Ashley is an Assistant Editor at Reader’s Digest. She received her Master’s Degree from CUNY Graduate School of Journalism in 2015. Before joining Reader’s Digest, she was a Jason Sheftell Fellow at the New York Daily News and interned at Seventeen and FOX News. When Ashley is not diligently fact-checking the magazine or writing for rd.com, she enjoys cooking (butternut squash pizza is her signature dish), binge-watching teen rom-coms on Netflix that she’s way too old for, and hiking (and falling down) mountains.