Technology Explained

Can F.lux and Night Shift Really Improve Your Sleep Habits?

Michael McConnell 19-04-2016

Over the last few years, people have perpetuated the idea that computer screens and mobile devices can harm our sleep 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 , which is why F.lux and Apple’s Night Shift have exploded in popularity. But do they actually work as advertised?


The answer might surprise you.

Sleep seems to be the one thing that all of us could use a little more of these days. We’re sleeping fewer hours per day than ever before, and staring into the bright lights of our computers and phones isn’t helping us get to bed any earlier — so let’s find out whether this trick is a real solution.

The Science of Sleep Deprivation

Before we delve too far into the science of sleep, do note that we aren’t a medical site nor are we medical professionals. Don’t take any of this as personal advice or guidance for your sleep habits. If you have any questions or concerns about your own sleep health, talk to your doctor.

The University of Maryland Medical Center advises that adults need between five and nine hours of sleep — where you fall on that spectrum is different person to person. Not everyone needs a straight eight hours.

That being said, studies have found a marked overall increase in insomnia and daytime sleepiness in modern adults. Just under 20% reported having trouble sleeping and around 10% reported excessive sleepiness throughout the day.


Sleepy Computing

What’s causing our sleep troubles? Harvard Sleep scientist Charles Czeisler places the blame squarely on our devices. Artificial light has hurt our sleep in general, but the LED lights in screens can exacerbate the problem.

Czeisler was involved in a study that compared reading on a tablet and a paper book in the same low light. Tablets were linked to taking longer to fall asleep and delaying REM sleep. The tablet group was also found to be sleepier in the morning.

The reason that LED causes more of a problem than other lights is that LED lights produce a color that’s far bluer than fluorescent or incandescent lights — and blue light is linked to reduced melatonin as well as increased alertness according to one study. Not only does it keep you from getting sleepy, it makes you more awake.


How Night Mode Apps Work

F.lux was one of the first apps to help fight the harmful effects of blue light Use F.lux To Sleep Better After Late-Night Computer Activities If you look carefully, most of LCD monitors have a button to automatically change the attributes of the screen to adjust for the types of media which is being viewed. Read More . Rather than simply dimming your screen, F.lux physically reduces the amount of blue light emitted by your screen, acting as a blue light filter What Is a Blue Light Filter and Which App Works Best? These blue light filter apps for Android will help you get a better night's sleep, even when using your device at night. Read More . The app warms up even further as the night progresses, allowing you to get a more natural light pattern.

It can take a bit of getting used to, as your screen is going to have a more of an orange look to it. The warmer colors obviously aren’t great for color-intensive work — such as photography or video editing — but these apps usually allow you to temporarily disable the warming when necessary.

Night Computing

Not long ago, Apple also debuted Night Shift as a tentpole feature in iOS 9.3. This works similarly to F.lux by reducing the amount of blue light emitted from the iOS device. It can be scheduled to run at a certain time, and you can adjust how warm it makes the screen’s color.


Android has a few different options available, like Twilight. There are some others if you are willing to root your device. An actual system utility is reported to be coming with Android N.

In other words, whether you’re using a desktop, laptop, tablet, or smartphone, you now have all kinds of options for reducing the amount of blue light that reaches your eyes during the night. That should mean that your insomnia issue is solved, right?

The True Efficacy of Night Mode

While these features are nice and they seem to make it easier to use a computer at night, what evidence is there that F.lux and Night Shift can help us develop better sleep habits?

A recent study tested this claim by using blue light filtering glasses and an app that filtered blue light to track the effects of these devices on sleep and melatonin production. (The app was un-named in the study, but was probably F.lux.)


The study found that the software and the glasses both reduced blue light’s effect on melatonin production.


The conclusion of the study was that devices and apps should come equipped with an automatic night mode, allowing the setting changes to happen automatically based on the light cycle in your area of the world. Which describes exactly what Flux and Night Shift are already doing.

Anne-Marie Chang, a sleep expert from PSU, said in an interview with Live Science that studies have shown this type of filtering can indeed reduce the effect of devices on sleep patterns. It should be noted that blue light isn’t the only thing affecting sleep patterns.

Blue Light Filters Aren’t Enough

One of the problems with the science of light filtering is that it’s just too new. Flux has been around for quite some time, but most of the research on their site is related to the effects of blue light.

There are only two studies linked on their page to the effects of filtering out blue light. One of them 404’s now, but both were related to improved mood and performance, not improved sleep patterns. Apple doesn’t cite any studies on the update page for iOS 9.3 and Night Shift.

On the other hand, red light has also been linked to sleep problems, even though it doesn’t have the same effects on melatonin. So despite reducing the harmful effects of blue light, other colors of light might still keep you awake.

Study Sleeping

Brightness can also be a factor in the amount of sleep you lose. If your device’s brightness is cranked to the max, filtering might help but you’re still going to be wide awake. Even on a completely black screen, max brightness still gives off a lot of light.

And light isn’t the only issue. When you’re on a device, you’re being mentally active — flipping between apps, responding to emails, taking one last peek at Twitter, browsing Reddit, etc. This keeps your brain active, leading to a correlation between social media use and sleep disturbance, similar to how bad TV habits can cause insomnia.

Better Sleep: More Than Night Mode

If you’re using your devices at night, filtering will help you. However, don’t expect it to fix all your problems. You’re far better off reading an unlit Kindle What Is E-Ink? How It Works & Why Every Ebook Fan Needs It If you read ebooks and haven't switched to E-Ink yet, then you're seriously missing out. Here's everything you need to know about why E-Ink rocks for ebook lovers. Read More or paperback book than taking your tablet to bed, even with filtering enabled.

Mitigating the damage isn’t a bad thing, but it isn’t the cure-all that many pundits have made it out to be. It should be said that most of these studies are correlative, but they do point to an overall effect. The science only seems certain of one thing: if you want a good night’s sleep, put your devices away a couple hours before bedtime.

If you need help with those bad habits, use these free printables and ebooks to track or change your habits 6 Free Printables and Ebooks to Track or Change Habits Habits aren't easy to change. These free printables and ebooks promise to help you track or change habits easily. Read More .

Image Credits: feeling tired when using tablet by leungchopan via Shutterstock, Anita Heart via Flickr, Lindsey Turner via Flickr, David Mulder via Flickr, alphaspirit via Shutterstock

Related topics: Geeky Science, Health, Sleep Health.

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  1. Ken Kline
    September 17, 2016 at 12:56 pm

    I have used F.lux off + on for years. I now have it on my iMac. If you want to experiment, just switch F.lux "ON" to see the maximum colour change it makes, then switch it "OFF" to see how harsh the regular blue light really is. After checking your article on the harmful effects of blue light, I am just configuring F.lux to start at login so I can get used to it on a regular basis. Also I have my screen brightness set at about a quarter of full brightness which is the "sweet spot" for me so these 2 settings give me not only the optimal viewing experience but also the least eye strain. Just my personal Experience.

  2. Anonymous
    May 22, 2016 at 1:26 am

    I use Lux with CF.lumen on my phone. Lux allows sub-zero brightness and CF.lumen does a great job with night mode and astro mode (all red).

    I've never really liked using a color shifting app on my computer. I don't use my computer much for things that don't require color accuracy so there really isn't much point for me to use one. The fact that I work 3rd shift also messes with f.lux setup because it seems to only work with sunset/sunrise and I go to bed at about 7 or 8 am.

    • Anonymous
      May 22, 2016 at 1:29 am

      I forgot to mention that I automate them with Tasker so I don't have to deal with the whole sunrise/sunset thing. I can schedule it to be whenever I want.

      • Michael McConnell
        May 22, 2016 at 10:29 pm

        I'm glad to see you found a setup that works with your schedule. I worked 2nd and 3rd shift for years, and it is always frustrating when these type of apps don't take shift workers into account.

  3. Anonymous
    April 30, 2016 at 3:06 pm

    I've used f.Lux for several years in Windows, and it definitely helps me to get off to sleep more easily. When I switched to Linux full-time a couple of years ago, I found that f.Lux only works on the command-line, and isn't very easy to set up.

    However, there is an alternative for Linux; RedShift (inspired by f.Lux):-

    Works very well, and the settings are, if anything, more comprehensive than f.Lux. Works well for me..!

  4. Tinh-Tanh M. Pham-Tran
    April 19, 2016 at 11:09 pm

    I'm a big fan of F.lux for a long time. I'd say that it helped my eyes a lot and I can work on a laptop for a long time. However, to improve my sleep quality (on my routine, recently), I have to put all the electronic devices away from my bedroom, and (usually start at 10 p.m) have at least 30 mins to an hour to meditate before sleeping (Could be stretching, or paying attention to your breath, etc. that can ease or let your mind go free, and especially without thinking or planning anything [this's a key point. If you wanna plan, do that in the early morning]).

    • Michael McConnell
      April 19, 2016 at 11:52 pm

      I have to admit I still read on my tablet before bed. Night mode has helped it be easier on the eyes, but I'm going to bed around the same time I did before it was installed.