What blue light filter does and why you might use it
Blue light filter on iPhone is a feature called Night Shift that makes your screen warmer and more yellow-orange instead of bright white. It does not block blue light entirely — no phone screen can do that — but it reduces the amount your eyes see, especially in the evening.
The idea is that blue light can make your brain think it is daytime, which can make it harder to fall asleep if you are using your phone close to bedtime. Night Shift dims the blue wavelengths your screen produces, so your eyes and brain get less of that signal. Whether this actually helps you sleep depends on how sensitive you are to light and how close to bed you use your phone.
Night Shift is free, built into every iPhone, and you can turn it on and off as many times as you want. It does not change what you are looking at — just the color temperature of the display.
Key Takeaways
- Night Shift is Apple's name for the blue light filter, and you turn it on through Settings > Display & Brightness > Night Shift.
- You can set it to turn on automatically at sunset and turn off at sunrise, or turn it on manually whenever you want.
- The warmth level slides from less warm to very warm, and you can adjust it to whatever feels comfortable to your eyes.
- Night Shift works on all iPhones running iOS 9.3 or later, which includes every iPhone model sold in the last eight years.
How to turn on Night Shift manually right now
The fastest way is through Control Center, which is the panel you swipe up from the bottom of your screen (or down from the top right on newer iPhones). Look for the icon that looks like a sun with a crescent moon — that is Night Shift. Tap it once to turn it on, tap it again to turn it off.
When you tap it, your screen will shift to a warmer color when ready. The change is noticeable — whites become yellowish, and the whole screen looks less bright and harsh. If it feels too warm, you can adjust the intensity by pressing and holding the Night Shift icon, which opens a slider.
How to set Night Shift to turn on automatically
Open Settings, then tap Display & Brightness. Scroll down and tap Night Shift. You will see a toggle at the top that says "Scheduled" — turn that on.
Once Scheduled is on, two time fields appear. The first says "From" and the second says "To". By default, it is set to turn on at sunset and turn off at sunrise, which uses your location to figure out when that is each day. If you want a fixed time instead — say, 9 p.m. to 7 a.m. — tap each field and set the times you want.
Below the times, you will see a slider labeled "Color Temperature". Drag it left for less warm (closer to normal white), or drag it right for more warm (more yellow-orange). The warmth you choose stays the same every time Night Shift turns on automatically.
Understanding the color temperature slider
The slider goes from cool (left) to warm (right). At the coolest setting, Night Shift is barely noticeable — your screen looks almost normal but slightly less blue. At the warmest setting, everything looks very yellow and orange, like you are looking at an old photograph.
There is no "correct" setting. Some people find the warmest setting most comfortable; others find it too extreme and prefer something in the middle. You can change it anytime by going back to Settings > Display & Brightness > Night Shift, or by long-pressing the Night Shift icon in Control Center.
If you have Night Shift scheduled to turn on automatically, you can still override it by turning it off manually in Control Center. The schedule will turn it back on at the next scheduled time.
What to do if Night Shift is not available on your iPhone
Night Shift requires iOS 9.3 or later. If you have an iPhone 6s or newer, you almost certainly have this version or a newer one. If you have an older iPhone, you can check by going to Settings > General > About and looking at the iOS version number.
If your iOS version is older than 9.3, you can update it by going to Settings > General > Software Update. Your phone will check for updates and read them if available. You will need to be on Wi-Fi and have at least 50 percent battery.
If your iPhone is too old to run iOS 9.3, Night Shift is not available. In that case, you can use a third-party app from the App Store that does something similar, though these are less reliable than the built-in feature.
Why your screen might not look warmer even though Night Shift is on
If Night Shift is on but your screen still looks bright and blue, the color temperature slider is probably set all the way to the left (cool). Go back to Settings > Display & Brightness > Night Shift and drag the slider to the right. You should see the change when ready.
Another reason is True Tone, which is a separate feature that adjusts your screen based on the light around you. True Tone and Night Shift can work together, but if True Tone is on, it might make Night Shift look less obvious. You can turn True Tone off in Settings > Display & Brightness if you want to see Night Shift more clearly.
Frequently Asked Questions
Does Night Shift actually help you sleep better?
Research is mixed. Some studies show that reducing blue light before bed helps people fall asleep faster, while others find no difference. It probably depends on how sensitive you are to light and how close to bedtime you use your phone. The safest approach is to put your phone down 30 to 60 minutes before sleep, but Night Shift costs nothing to try.
Can I use Night Shift during the day?
Yes. Some people turn it on whenever they use their phone for a long time, because the warmer screen can feel less harsh on their eyes. You can turn it on and off as many times as you want, and it will not damage your phone or your eyes.
Will Night Shift make colors look wrong in photos or videos?
Night Shift only changes what you see on your screen — it does not change the actual photo or video file. If you are editing photos or doing color-sensitive work, you might want to turn Night Shift off temporarily so you see the true colors. Once you turn it back on, the file itself is unchanged.
What is the difference between Night Shift and reducing brightness?
Reducing brightness makes everything darker, which can help your eyes feel less strained. Night Shift changes the color of the light without making it darker. You can use both at the same time — lower brightness and Night Shift on — if you want the most comfortable viewing experience.