Night Shift in iOS 9.3: Explained!

iPhone 6s Plus
iPhone 6s Plus (Image credit: iMore)

With iOS 9.3 Apple is introducing a new feature called Night Shift. As the name implies, it shifts the color spectrum of your iPhone or iPad display at night. So, why is that important?

Read how to use Night Shift on iOS 9.3

Light and the brain

During the day we soak in light from the sun. Unlike Superman or Supergirl, to whom it grants unbelievable power, in us the light suppresses melatonin. As it gets darker we produce more melatonin. It usually starts a few hours before bedtime and increases greatly towards the middle of the night. That helps keep us asleep and ensure we get a good night's rest.

Shorter wavelength blue light, by contrast, does the opposite: It suppresses melatonin and builds up histamine that helps wake us up. Unfortunately, electronic displays like those on phones and tablets have a higher concentration of blue light than the sun. So, when you're lying in bed at night playing Candy Crush, watching YouTube, or reading iMore, you're soaking in the blue light and wreaking havoc with our circadian rhythm. In other words, it resets that feeling of tiredness and hurts our sleep cycle.

And we need sleep. We do most of our healing when we sleep. It's when our bodies repair themselves and our minds process the information we accumulated during the day. Lack of sleep can have an extremely adverse affect on our mental and physical health. It can interfere with our brain's ability to form memories efficiently and even reduce our immunity to disease.

Night shift

That's where Night Shift comes in. When you enable Blue Light Reduction in the Display & Brightness settings, it moves the color spectrum from cooler (blue) towards warmer (yellow).

You can enable it at any time but what's really nice is that you can schedule it as well. There's a default that shifts from sunset to sunrise, but you can also set your own custom schedule if you prefer.

If you simply play around with it, the yellow might look really yellow. Our brains are amazing at adapting, though. When it happens on schedule we adjust to it and reset what we perceive as white. So, after a while, the shift towards yellow is as barely noticeable as the usual shift towards blue is.

The bigger picture

Of course, Night Shift only addresses part of the problem. Using your iPhone and iPad at night, especially for highly-engaging activities like video games, social networking, and messaging can also keep you awake and mess with your sleep hygiene.

Use Nightshift to help you wind down, but when it gets time for sleep, do yourself a bigger favor and just put your devices down!

Night Shift is currently available as part of the iOS 9.3 for 64-bit devices. That includes iPhone 5s and later.

Originally published January 18, 2016.

Senior Editor at iMore and a practicing therapist specializing in stress and anxiety. She speaks everywhere from conferences to corporations, co-host of Vector and Isometric podcasts, follow her on Twitter @Georgia_Dow and check out her series at anxiety-videos.com.

77 Comments
  • I doubt seriously that night shift will help me sleep. It will, however, be easier on my eyes. And that's a big plus with me!
  • I do think it'll help, even if just a bit
  • As someone who had horrible sleep habits a few years back, I feel like f.lux definitely gets props from me in helping correct my habits. I downloaded it for my laptop and set it to automatically adjust to the lowest setting at bedtime and after a few weeks, there was a considerable improvement in the time I could fall asleep. I used to stay up till 4am every day and sleep all day and trying to get back on a normal sleep cycle was brutal. Everyone works differently though. Hopefully it ends up helping you though because f.lux is basically a necessity to me now and I only notice when it's not on.. because my eyes will physically start to ache after a few minutes(even on the lowest brightness setting on my laptop). Honestly I would pay pretty good money for an app like this if they had chosen to go the paid route rather than free because the benefits are great. I seriously doubted it at first because I hated the orange tint it gave everything, but you get used to it quick
  • This article did what night shift couldn't accomplish. I just woke up with my iPhone on my chest. Thanks Georgia Sent from the iMore App
  • Great explanation, Georgia. Makes perfect sense!
  • How come Apple isn't adding this to OS X, watchOS, and tvOS? Doesn't a lot of the value of this go away if you also use the other platforms at night?
  • Although Apple has not added this yet, there is a free app called F.lux https://justgetflux.com/ for the OS X which does the same thing as Night Shift.
  • What about tvOS?
  • That you may have to wait until a sideload alternative appears or Apple finally decides to implement it. I seriously don't know why Apple is so obsessed with all white everywhere UI crap and calls it elegant.
  • Yes, but it's not an app and makes you jailbreak the phone, correct?
  • He's referring to the OSX version. But you are correct about the iOS version, it's not an app and you have to jailbreak to install since Apple shut it out (to make room for NightShift, no doubt)
  • Not exactly, but it is a hassle to side load for iOS .. On a couple of my devices I have both flux and night shift; if I feel brave I'll try turning both on at once! I would love it for tvOS though, wouldn't surprise me if it pops up next update. Had a similar thing when using a (flux) Mac HDMI with hotel TV and it was brilliant(or the opposite, very nice on the eyes later at night)
  • For tvOS- adjust your tv. Change the color temp to warm. Turn down the backlight (if available) (different than brightness). Maybe adjust the brightness a little.
    My TV has different display setting presets, I've saved one for exactly this. Sent from the iMore App
  • I've done this too but having it auto drop a degree every minute nice and smooth is very cool.. Warm. Argh!
  • Saw my friends phone with the 9.3 Beta and it took a bit for my eyes to get used to but I can see how it will be a benefit. Look forward to it. I never really thought of using my phone before bed as a problem but will be interested to see whether this improves my sleep in anyway.
  • Yeah I never really thought of it as a problem either up until I used f.lux on my laptop for a few months and then made the mistake of turning it off in the middle of the night to see some colors in a picture better. I haven't used night shift but it's basically the same thing as f.lux so I can almost guarantee it'll be great. I'm really glad Apple is doing this because I just made the switch from android to iOS and f.lux was the first app I searched for on the app store.
  • Blue light is no issue for me. I fall asleep most nights dropping my tablet in my face or on my chest. Wouldn't like the look of the orange/yellow hue either. I changed all my bulbs in the house to the blue tint daylight style.
  • I have no problems sleeping either. However it is much much easier on the eyes and strains them less. Especially useful after I spent the entire day studying in front of a computer. I also thought I would dislike it but I got used to it very quickly. Sent from the iMore App
  • You get used to the orange hue when you have it set to automatically change with sunset/sunrise, it's quite a slow gradual change if you're used to using your phone a lot
  • Is there an option for it to automatically change when the sun sets and rises then?
  • I don't have the beta but I have used f.lux for several years and if Apple follows their model at all, there will be an option for that. On my macbook, I can set what time I plan on waking up at and it'll automatically adjust the colors based on what part of night it is. Mine is set to be at normal during daylight and once the sun starts to set, it gradually changes to warmer and warmer colors until it hits 1200k which is the lowest setting possible for f.lux on OS X. You can also set it to instantly change if you prefer that over gradual change for some reason. I prefer the gradual change because it lets my eyes adjust to the color change over a period of a couple hours.
  • So because of this feature.. It won't be "necessary" for a Dark mode (also)? I think that yellow light make it look....too yellow. Why not make a Dark mode also? I enjoy viewing articles in Reader mode. Why can't reader mode exist in iMessage, Mail, Settings etc? The UI there is so white and shouldn't be hard to implement there also? Sent from the iMore App
  • You get used to the yellow hue when you have it set to automatically change with sunset/sunrise, it's quite a slow gradual change if you're used to using your phone a lot
  • Why this is not working on iPhone 4s? Sent from the iMore App
  • Atm this feature will only be implemented on 64 bit iPhones.
  • You MIGHT be able to side load F.Lux on your phone. https://www.google.co.uk/search?ie=utf8&oe=utf8&q=flux+side+load&gws_rd=...
  • ffs..!! So that's why I'm not seeing it on my iPad.
  • Not at this moment. Will definitely be for A7+ devices Posted via the iMore App for Android
  • I'd be happy to have a dark theme rather than a shift in my display. Oh well. Sent from the iMore App
  • I've had f.lux on my Mac for years. If you can't recognize the ease your eyes obtain viewing a screen that is orange or Amber instead of blue, I feel sorry for you. I am beyond thrilled that Apple has finally allowed me to make my screen Amber, but I hope they allow f.lux access so that their full-feautured app can be enjoyed across all apple products. I don't work for f.lux, but now Apple has shown us that you do not need to jailbreak your iPhone to have an amber screen.
  • Nice Read/article Georgia.
  • Looking forward to try this out.
  • I hope they put a toggle in control center and not go all the way deep in settings to activate it!!
  • I use the Launcher Today Widget with a launch icon for the Display settings tab and it makes access to Night Shift Mode easy, but I just have it set to Sunset to Sunrise. Sent from the iMore App
  • Not sure about a toggle in Control Center, but I've seen a screen shot of the public beta, and there is indeed a slider for "warmer" and "colder" so it is entirely adjustable. Some people were worried that Apple would only offer one color setting.
  • They should push a Tip about Night Shift seeing as how many out of the few here commenting have not ever heard of such a feature.
  • Night shift is always turned on. I'm glad Apple brought this feature to iOS without having to jailbreak. Sent from the iMore App
  • Hope it can be turned off. Dont want it personally. Just more bloat for my needs.
  • You can turn it off, but it really doesn't have any bloat. It's not its own app, it's just an extra setting under display/brightness, and all it does is tint the screen
  • They could have at least credited F.lux.
  • Just like every "new" feature on every OS credits the previous use?
  • Because every feature that copies iOS always gives proper credit to Apple?
  • Why credit F.lux? This is all based on research going back decades. It's not like F.lux discovered this problem and uniquely solved it.
  • Why I don't think they were the first or invented this feature Posted via the iMore App for Android
  • Tried it out and didn't like the way the display seemed washed out. No thank you. Sent from the iMore App
  • You get used to the orange hue when you have it set to automatically change with sunset/sunrise, it's quite a slow gradual change if you're used to using your phone a lot
  • I can vouch for this from using F.lux...eventually you don't even realize that it's on.
  • What @DannyJJK said... you get used to it. Didn't like it at first, but just set it in the middle, put it on sunset to sunrise, and forget about it. You'll see it at first, but it's subtle enough to not be distracting. Felt the same way as you did but now I am excited to see if I can tell any difference. May not be able to but I'm thinking it can't hurt. :)
  • All modern digital devices produce harmful Blue Light. This short wave length light is known to cause eye strain and fatigue, as well as to increase the likelihood of eye diseases. It solves the problem partially , it can help me only at the time of night. What about day time? I think we must use blue light protector for our own safety. Because this feature is available for iOS 9.3. That's why I have bee using "OcuShield" screen protector for last three months.
  • I think you're taking this a bit to the extreme, blue light won't cause eye diseases. No one's going to die from looking at a display
  • How do you know? Sent from the iMore App
  • Keep wearing your tinfoil hat
  • I like the shift to sunset and twilight colors, but it won't do me any good until my Mac does it too...
  • You can use F.lux on your Mac to achieve the same effect
  • "...when it gets time for sleep, do yourself a bigger favor and just put your devices down!" This is kinda how I feel about this whole issue... We shouldn't be so glued to our devices, but that problem probably isn't going away, so kudos to anybody trying to alleviate it, I guess...
  • Some people want to use their devices before they go to sleep, to read a book or whatever.
  • I completely understand that. Here, though, it's apparent that even Apple doesn't think that's a good idea **on a lit-up screen**, but they're not saying as much - they're just trying to minimize the impact.
  • I have iPod touch iOS 9.2 When is iOS 9.3 being released on iPod touch?
  • Soon when it's out of beta Posted via the iMore App for Android
  • If you're "brave" you can get onto the beta, it's pretty stable for me on iPads air 2, mini 2 and iPhone 5S.. Haven't tried on my primary 6S yet.
  • It seems to put me to sleep, when I want to stay up reading. It is a great feature.
  • Hi Georgia. You say that, "During the day we soak in light from the sun" and that this light "builds up melatonin." This is actually not correct. Sunlight, in fact, depresses melatonin production. This is so we stay awake and alert during the day. Before artificial light, our levels of melatonin would naturally increase as soon as the sun went down, causing us to become sleepy. And then as soon as the sun rose again, our melatonin would decrease, helping us wake up. I think your confusion comes from the fact that while sunlight may appear yellow to us, it is, in fact, quite blue. The atmosphere diffuses the blue and violet wavelengths, causing us to see mostly yellow and orange, but our body is still reacting to the blue wavelengths (this is because it's not our rods and cones that are responsible for melatonin regulation, it's different cells known as melanopsin-containing ganglion cells.). So when we look at light emitting devices, our bodies react to the blue wavelengths they emit in the same way they react to the blue wavelengths from the sun, causing melatonin production to be depressed. So the end result is the same, but the premise you use to get there isn't quite accurate.
  • Wow... I just learned a LOT of things.
  • Yes you are right, it actually happens the first few hours before bed thats when we build up the most melatonin.
  • Why is this a problem? Just turn off the device. Viola! Instant darkness.
  • Some people want to use their devices before they go to sleep, to read a book or whatever
  • Agreed...your personal use case should be applied to everyone else!
  • The lack of darkness isn't the problem - it's the fact that artificial blue light has stimulating effects on your eyes that can delay the amount of time it takes to fall asleep and add unnecessary strain. There's decades of research on this going all the way back to when researchers studied bird migratory habits(not sure how bird migration ties into blue light keeping humans awake - the paper that f.lux linked to didn't say). This is basically the answer to "how can we mitigate the stimulation and strain caused by our screens on our eyes/sleep habits?" not "how can we make it darker?". Some research even concluded that the color temperature of your screen has more of an effect on your eyes and sleep habits than the illuminance of the screen, and other results also concluded that reduction of that illuminance without a reduction in color temperature should be avoided as much as possible. So turning off the device really doesn't do **** in regards to what night shift was developed for.
  • The last paragraph of this article is the best one instead of adding this F.lux-like feature that I will never use. I am already sleepy after getting home from work and all info is put my phone to charge and pass out. Good night. Sent from the iMore App
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