Discovery Hub

Your Cell Phone Use and Sleep: How to Reduce the Effects of Blue Light


February 08, 2019

We’ve all heard that it’s best to keep your cell phone and other devices out of the bedroom while you’re trying to sleep, but do you know why? Blue light is mostly to blame.

Full-spectrum screens like those found on computers and cell phones emit a lot of blue light — the same spectrum of light emitted by the sun that tells our brains it’s daytime.

Blue light may make your phone screen look good, but it can also wreak havoc on your ability to sleep.

As the sun goes down, the natural light that reaches us gets redder, and dimmer. These light cues are what tell our brain to start producing melatonin, the hormone that makes us fall asleep. Our screens, on the other hand, always emit the same amount of blue light; therefore, the more we look at screens before bed, the harder it can be to sleep soundly.

What to do about blue light

If you’re able, give yourself a technology curfew — no phones, computers, or television at least 30 minutes before you go to sleep.

  • If you use your phone as an alarm clock or for white noise, set it up and then turn the screen off while you get ready for bed.
  • If you read in bed, read a physical book, or use an e-reader that mimics paper (look for one with no backlight or LCD) instead of reading on your phone.
  • Use warm-colored bulbs in your bedroom to help send your brain the message that it’s bedtime, and give yourself as much time as possible to wind down without the stimulating effects of your devices.

When you can’t avoid it

In this tech-driven world, it’s not always possible to avoid screen time before bed. So, if you need to use your devices at bedtime, what can you do to minimize blue light effects on sleep?

Blue light-blocking glasses are available to filter out the blue light emitted by your phone. Using them right before bed can help prevent the light from suppressing your melatonin, which might help you get better-quality sleep. Several apps are also available to help, and they work the same way: download the app, add your location, and let it control your device’s display color for you.

For example, night screen apps like Twilight (Android), Iris (iOS), and f.lux (Windows, Linux, and Mac OS) adjust the display automatically based on your location and time of day, matching the color of your screen with the natural rhythms of light around you. Your device will display normally during the day, but starting at sunset, it will gradually become dimmer and redder, minimizing the effect of blue light on your brain and decreasing eye strain.

Many of these apps allow you control how much you want your screen to dim, and you can also turn it off if you need to do a color-sensitive task like illustration, graphic design, or stream a film.

Cell phones, computers, and other screens look so good because they mimic the natural light of day. But while that makes them nice to look at, it also means they can confuse our brain and our natural cycles, keeping us awake by preventing the natural release of melatonin. It’s best to eliminate screens before bed, but if that’s not possible, using an app that removes blue light can help when you must use your computer or phone at night.

iPhone 14 Pro

iPhone 14 Pro

Experience iPhone in a whole new way with Dynamic Island and Always-On display.

Shop iPhone