Apps Can Cut Blue Light From Devices, But Do They Help You Sleep?

Nov 27, 2017
Originally published on November 27, 2017 12:13 pm

If you're losing sleep over the blue light coming from your phone, there's an app for that.

In fact, there are now lots of apps that promise to improve sleep by filtering out the blue light produced by phones, tablets, computers and even televisions.

But how well do these apps work?

There haven't been any big studies to answer that question. So I phoned a couple of scientists who study the link between blue light exposure and sleep.

My first call is to Lisa Ostrin, an assistant professor at the University of Houston College of Optometry.

Ostrin owns an iPhone. And every iPhone comes with an app called Night Shift that lets you filter out blue light. So does Ostrin use Night Shift?

"Yes I do," she tells me.

Without a filtering app, cellphones and tablets expose users to an alarming amount of blue light, she says, "Especially as people are lying in bed and have their screens just a few inches from their face."

And all that blue light prevents special photoreceptor cells in the eye from triggering the release of a sleep hormone, she says.

"Normally when the sun goes down and the lights turn off, our body releases melatonin, which helps us get a nice restful sleep," Ostrin says. "But when we have all this artificial light on, it's tricking those photoreceptors into thinking it's still daytime."

Ostrin was part of a team that showed this in a study published this summer in the journal Ophthalmic & Physiological Optics.

In the study, 21 people put on special glasses after sunset each day to filter out blue light. "So essentially we blocked the input to those photoreceptors that tell our body it's still daytime," she says.

After two weeks, the participants' melatonin levels had increased by 58 percent. And they reported better sleep.

Apps that filter the light from device screens are less effective than blue-blocking glasses, Ostrin says, but still can help. "I highly recommend them," she says.

To get a different perspective, I call Brian Zoltowski at Southern Methodist University in Dallas.

Like Ostrin, Zoltowski studies blue light and sleep. And he also owns an iPhone. But "I am not a Night Shift user currently," he says.

Zoltowski used to use the app. He also found ways to reduce the blue light coming from all of his other screens during the evening.

The downside was that everything he saw in the evening was some shade of orange. And he wasn't sure he was sleeping any better.

"So I'm looking at an orange screen watching a video realizing I'm also drinking a cup of coffee," Zoltowski says. "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."

He also realized he just didn't like looking at all those orange screens. So he turned off Night Shift and all the other blue light filters on his devices.

"I'm willing to take the blue light exposure for the improved quality of the images," he says.

Zoltowski says people need to remember that devices are just one source of blue light. Others include indoor lighting, streetlights and car headlights.

So he says a filtering app may not be worth it, especially if you're already getting a good night's sleep, he says.

"But if you suffer from sleep problems and you've tried other things like eliminating caffeine later in the day," he says, "this is something you can add to your repertoire to promote a healthful sleeping environment."

If you're serious about getting better sleep, though, you might want to avoid screens entirely near bedtime, Zoltowski says. "Try to wind down, shut down your devices, dim the lights, relax and maybe read a book the old fashioned way."

At least one study found that people took longer to fall asleep when they read from a light-emitting e-book than when they read from a printed book.

Copyright 2017 NPR. To see more, visit http://www.npr.org/.

DAVID GREENE, HOST:

OK, now let's talk about some light that is probably not as good for you. This is the light coming from your smartphone or other screens. It's known as blue light. And it can really interfere with your sleep. Some people are using apps to filter out some of that blue light. As for how these apps actually work, NPR's Jon Hamilton reached some scientists.

JON HAMILTON, BYLINE: The first person I called is Lisa Ostrin at the University of Houston College of Optometry. She studies the effects of blue light on sleep. She also owns an iPhone. And every iPhone comes with an app called Night Shift that lets you filter out blue light. So I ask Ostrin, do you use it?

LISA OSTRIN: Yes, I do.

HAMILTON: Ostrin says without a filtering app, cell phones and tablets expose people to a lot of blue light.

OSTRIN: Especially as people are laying in bed and have their screens just a few inches from their face before bedtime.

HAMILTON: And Ostrin says all that blue light prevents photoreceptor cells in the eye from triggering the release of an important hormone.

OSTRIN: Normally, when the sun goes down, and the lights turn off, our body releases melatonin, which helps us get a nice, restful sleep. But when we have all this artificial light on, it's tricking those photoreceptors into thinking it's still daytime.

HAMILTON: Ostrin's own research has shown that it's possible to prevent this. She had 21 people put on special glasses after sunset each day to filter out blue light.

OSTRIN: So, essentially, we block the input to those photoreceptors that tell our body it's still daytime.

HAMILTON: And it made a difference.

OSTRIN: What we found was a dramatic increase in their nighttime melatonin levels after two weeks of wearing these glasses.

HAMILTON: Participants also reported better sleep. To get another perspective, I called Brian Zoltowswki at Southern Methodist University in Dallas. Like Ostrin, he studies blue light in sleep, and he owns an iPhone.

BRIAN ZOLTOWSKI: I am talking to you on an iPhone right now. And I actually am not a Night Shift user currently.

HAMILTON: Zoltowski says he did use the filtering app. He also took steps to reduce the blue light coming from other screens during the evening. And he says that made every image look kind of orange.

ZOLTOWSKI: So I'm looking at an orange screen, watching a video, realizing I'm also drinking a cup of coffee. And it started to make me wonder then why I'm actually trying to, you know, 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.

HAMILTON: Also, he really didn't like all those orange screens.

ZOLTOWSKI: I'm willing to take the blue light exposure for the improved quality of the images.

HAMILTON: Zoltowski adds that devices are just one source of blue light. Others include indoor lighting and street lights. So he says a filtering app may not be worth it, especially if you're already getting a good night's sleep.

ZOLTOWSKI: But if you suffer from sleep problems, and you've tried other things like eliminating caffeine later in the day, this is something that you can add to your kind of repertoire of making sure that you're doing everything you can to promote a healthful sleeping environment.

HAMILTON: Zoltowski says you might also just give up screens entirely around bedtime. At least one study found that people got more sleep when they switched from electronic readers to printed books. Jon Hamilton, NPR News.

(SOUNDBITE OF MOKHOV'S "EUPHORIC MAGIC") Transcript provided by NPR, Copyright NPR.