Does iPhone's 'Night Shift' actually help you sleep?

Editor's note: This popular story from the Daily Briefing's archives was republished on Nov. 14, 2018.

Many applications claim to improve sleep by filtering out blue light emitted by computers, tablets, and phones—but absent robust research, their effectiveness is up for debate, Jon Hamilton writes for NPR's "Shots."

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Hamilton notes that little reliable scientific research has examined apps that claim to improve sleep. So he reached out to two experts who study the link between blue light exposure and sleep: Lisa Ostrin, an assistant professor at the University of Houston College of Optometry, and Brian Zoltowski of Southern Methodist University.

Do sleep aid apps work?

Ostrin says that she uses the iPhone's Night Shift app to help filter out blue light in the evening.

She explained that blue light emitted from phones, computers, and tablets prevents photoreceptor cells in the eye from signaling for the release of the sleep hormone melatonin. "Normally when the sun goes down and the lights turn off, our body releases melatonin, which helps us get a nice restful sleep," she said. "But when we have all this artificial light on, it's tricking those photoreceptors into thinking it's still daytime."

Ostrin cited a study published in June that she worked on that found melatonin levels in people who wore special glasses that filtered out blue light rose by 58%, and the study participants reported better sleep.

While apps that filter blue light are different than the glasses used in the study, Ostrin says that she "highly recommend[s] them."

Zoltowski, on the other hand, no longer uses blue light filtering apps. He said the apps—which reduce blue light exposure by making the screen orange—decreased the viewing quality on his screen and did not compensate for other habits that contribute to poor sleep, such as consuming caffeine.

"So I'm looking at an orange screen watching a video realizing I'm also drinking a cup of coffee," Zoltowski said. "And it started to make me wonder then why I'm actually trying to decrease the amount of blue light when the caffeine that I'm drinking in my cup of coffee is probably having a larger effect on my sleep quality."

For those who feel they are getting a decent night's sleep, Zoltowski said apps to reduce blue light may not have any additional benefits.  "But if you suffer from sleep problems and you've tried other things like eliminating caffeine later in the day," he said, "this is something you can add to your repertoire to promote a healthful sleeping environment."

According to Zoltowski, however, the best option for those with trouble sleeping is to unplug from electronic devices before bed, as at least one study found that individuals who read a paper book were able to fall asleep faster than those who used an e-reader. "Try to wind down, shut down your devices, dim the lights, relax, and maybe read a book the old fashioned way," Zoltowski said (Hamilton, "Shots," NPR 11/27).

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