Android Technology Explained

What Is a Blue Light Filter and Which App Works Best?

Andy Betts Updated 28-01-2019

How often do you get a good night’s sleep? If the answer is anything less than “always,” then you might want to consider the impact your gadgets have on your nightly slumber.


While it’s common for many of us to unwind in the evening reading ebooks, watching Netflix, or catching up on Facebook, experts are united in their belief that this is not healthy.

The problem is that screens emit blue light that tricks our brains into thinking we should be awake. The easy solution to this is to use a blue light filter on your Android phone. Let’s take a look at exactly why you need one, and which is the best to use.

The Problem With Blue Light

Studies, such as one done by Harvard, have repeatedly warned that using gadgets in the evening affects both the quantity and quality of our sleep. It’s a often-told techology tale that is true Fact or Fiction? 6 Myths About Screens and Monitors How many screen-related myths have you heard? Does looking at a screen in the dark hurt your eyes? The truth might surprise you. Read More .

The cause is exposure to light at nighttime. More specifically, it’s exposure to short wavelength blue light—the kind given off by our phones and tablets and pretty much any gadget with an illuminated display.

blue light measurement android


Sunlight also contains blue light, which is vital during the day. It’s what helps to keep us awake and alert, and is an integral part of how sleep cycles work.

But exposure to blue light at night is negative, as it effectively tricks your brain into thinking that it’s still daytime. It suppresses the secretion of melatonin, a hormone that is produced at night and prepares the body for sleep, as one NHS study shows.

Its impact is so great, in fact, that another study reported by the Daily Mail even suggested that having a blue LED shining from a car dashboard would be an effective way of preventing drivers from falling asleep at the wheel.

So what do you do, short of turning your phone off hours before you go to bed?


Head into the Play Store, and you’ll find numerous apps that provide the solution: filtering out the blue light entirely.

blue light filter apps

What Does a Blue Light Filter Do?

Most blue light filtering apps work in a similar way. They do nothing during daylight hours, but after sunset place a red overlay on the screen to change its color temperature.

blue light filter android


This gives everything a red hue, which takes a little getting used to. But it also cancels out the negative effects of the blue light, and massively decreases glare. Even if you’re skeptical about it improving your sleep, you will immediately notice a reduction in eye strain when using your phone in a dimly lit room.

However, the apps aren’t perfect. Their use of a red overlay reduces contrast, and it turns blacks into a dark shade of red.

They can also trigger a security feature in Android where certain buttons become inaccessible when overlays are in place. You’ll most likely notice it if you attempt to install an app from an alternative app store The 4 Best Google Play Alternatives for Downloading Android Apps Don't want to use the Google Play Store? Or don't have access to it? Here are the best alternative app stores for Android. Read More . To tap the Install button, you have to pause or close the filtering app. Many also don’t work on your notifications pane.

The Built-In Option: Night Light

First, you should check whether you’ve already got a blue light filter on your phone. Android 7 Nougat introduced one, although manufactures don’t always choose to include it in their build of the operating system.


So if you’re running Android 7 or later, go to Settings > Display and look for an option labeled Night Light. On a Samsung Galaxy you’ll find it in the Quick Settings panel, where it’s called the Blue Light Filter.

If it’s there, you’re good to go. You can schedule it to turn on automatically, and adjust the intensity of the effect. If not—or if you want more fine-tuned control—you’ll need to install an app.

Best Overall Blue Light Filter App: Twilight

Twilight is the best blue light filter app for Android. It progressively reduces the color temperature of the display (making it redder) and dims the screen until it reaches your chosen levels of color and brightness.

This gradual change means that you barely even notice it happening. At first whites are no more than slightly off-white, but by the time you’re in bed browsing Reddit, the effect will be in full force.

By using your phone’s light sensor, Twilight is able to constantly adjust its settings automatically, ensuring they always suit your ambient lighting conditions. Once you get past the initial setup, you’ll never need to touch the app again.

Two features make Twilight especially useful. One is that you can set it to disable automatically when you’ve got certain apps open. This way, it won’t disrupt your Netflix viewing. The other is that it works with Philips HUE smart bulbs, allowing you to make your home’s lighting as sleep-friendly as possible. If this sounds interesting, check out how to sleep better with a smart home.

Download: Twilight (Free) | Twilight Pro ($3.49)

The Root Option: Night Light (KCAL)

Twilight is the best choice for most users, but if your phone is rooted, you’ve got the option to use a more powerful app in the form of Night Light.

As a root app, Night Light is able to directly control the display. Instead of placing a red overlay on the screen to cancel out the effect of the blue light, it literally reduces the amount of blue light that the screen outputs.

The result is a higher-quality image. Night Light doesn’t give everything a red tint—blacks remain black, for example—and there’s no loss of contrast. It also doesn’t interfere with your notifications or other apps.

You need to root your phone to use Night Light, and you might need to install a custom kernel.

Download: Night Light (KCAL) (Free)

Reduce the Effect of Blue Light Without Filtering It

The reddening effect of blue light filtering apps is a little strange, but it’s fairly easy to get used to. Still, some people just don’t like it. If you’re one of them, there are still ways to minimize the effects of blue light.

The key is to reduce the amount you are exposed to. So using a phone instead of a tablet is better due to the smaller screen. Reduce the brightness as much as you can, and if you use apps that have a night mode or dark theme The 12 Best Android Dark Mode Apps You Should Install Have an Android phone with an AMOLED screen? Here are the best Android apps with dark mode that are worth installing. Read More , enable them.

Most ebook readers have a white-on-black or sepia options. Both are more eye-friendly than the standard black text on a white background. Google Play Books goes a step further, offering its own Night Light feature. It turns on automatically at sunset, and gradually removes more blue light from the display the darker it gets.

To activate this feature, open a book, tap the Display Options button, and hit the Night Light toggle.

Sleep Better With Android

Apps like Twilight enable you to use your Android phone freely without it stopping you from falling sleep, or leaving you feeling groggy in the morning. But it isn’t the only way your phone can help you sleep better.

Our guide to the best sleep apps has unmissable recommendations for everything from sleep meditation apps to smart alarms that will wake you up at the optimal time each morning. They’ll help you feel more rested and refreshed than ever. We also have a roundup of apps and methods that can help you fall asleep faster.

And if it’s an addiction to your smartphone that keeps you up The 5 Best Apps to Help You Fight Your Smartphone Addiction Are you addicted to your smartphone? These mobile apps will help you salvage your personal life and regain your productivity. Read More , take a look at these apps that can help:

Image Credit: Mila Supinskaya/Shutterstock

Related topics: Android Apps, Android Customization, Android Tips, Health, Sleep Health, Sleep Mode.

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  1. Ebi Chijioke Esq
    June 15, 2019 at 4:34 pm

    I read from Nigeria, severally your articles are well balanced (sic my view of course) not too critically like some hard online marketers who are inclined to promote a product to make a sale, and cunningly discredit other products.
    I am an engineer, I believe every products are not made to meet everyone expectations.

  2. Liel
    October 28, 2017 at 5:35 pm

    Is there a Bluelight Filter App that doesn't consume your battery? I used a Night Filter App that just killed my battery (and I have a healthy battery).

  3. Luis Francisco
    February 23, 2017 at 2:14 pm

    Muito obrigado!
    means, thank you very much, in Portuguese
    I'm trying Twilight

  4. Amy Lecter
    July 6, 2016 at 6:23 am

    iPhone has the Night Shift to block blue light on iOS 9.3 and up. And I am now wearing a pair of T'aime blue light blocking glasses, F.lux installed in conjunction when working in front of computer. Sometimes I choose to turn off F.lux since it can distort the color perception and decrease brightness on my screen. Indeed, a decent pair of blue blocker glasses is in need.

  5. Heather Phillips
    January 22, 2016 at 4:23 am

    I have severe insomnia and take medication. I could not understand how I was having nights where it was like I didn't even take medication. It was getting so bad I thought the medication wasn't working. I had never heard of the issue of bluelight and then realized I had been binge watching Netflix and Itunes the nights I was having trouble sleeping. Downloaded the app f.lux on my laptop and have slept like a baby ever since. Can't believe I was using my laptop all the years at night not realizing the bluelight could have been the reason my insomnia had gotten so bad. Love the f.lux app! Amazing and has great features. :)

  6. suman
    December 14, 2015 at 7:49 am

    Alan the glass you are talking about only block 40% of blue light they do not block 99% which is required to produce melatonin for the body 40% reduction will protect the retina but unfortunately will not help with melatonin production or Sleep Phase Delay Disorder.

  7. Anonymous
    October 10, 2015 at 6:15 am

    This article failed to mention that if you wear glasses that there are lenses that specifically filter blue light (BluTech), as well as, several lens companies that have incorporated blue light filters into their anti-reflective coatings, reducing both harmful blue light and annoying glare. Hoya lenses makes the Recharge coating; Essilor's coating is called Provencia, and there are several others available.

  8. Anonymous
    October 7, 2015 at 10:09 pm

    Not sure if this is true or not but was a longtime twilight user for an IPS screened android. Switched over to an AMOLED screen then made a little research. Apparently, using the red filter can wear or the red pixels on an AMOLED screen. Like I said, not sure if it's true, but I stopped using the red filter and just used the lowered screen brightness.

  9. Anonymous
    October 6, 2015 at 9:23 pm

    I am using f.lux for about two weeks now. And I am not feeling any itchiness in the eye when I wake up. It's really amazing. Already recommended to several friends.

  10. Anonymous
    October 6, 2015 at 7:12 am

    I used Lux in the past, due to it's erratic behaviour (or Bug), I switched to a simpler solution, Bluelight Filter.

    Lux is far advanced and has more features. Bluelight Filter just does the work, I am happy with it.

  11. Anonymous
    October 6, 2015 at 3:25 am

    On the Kindle app and Google's Play Book app I use the Night Mode (white text on black background) all day long, I find it much less strenuous.

  12. Anonymous
    October 5, 2015 at 8:26 pm

    CyanogenMod 12.1 has that feature built into the system, called LiveDisplay.