Compatible with devices running iOS5/6/7/8.

f.lux warms up your screen to match your lighting at night.

If you see the f.lux app crash when launched, it seems to be incompatible with Medusa right now: thanks reddit for the report.

Older iOS versions: Sometimes when updating Cydia and f.lux at the same time, the Reboot Device button will not work, and f.lux will not run. If you encounter this, please reboot the device (don't respring) to fix it.

Have you ever seen someone using a mobile phone in a bar or dark restaurant and noticed the bright blue glow coming from the screen? f.lux fixes this.

Select the type of lighting in the room you're in at night, and then forget about it.

Each evening at sunset, f.lux warms up the colors on your phone. At dawn, f.lux returns your phone to daylight colors.

We made f.lux because one day we noticed that all our laptops were the wrong color temperature at night. They looked fine during the day, but at night, they were much too blue. We realized that looking at the sun all night long might not be such a good idea.

After researching blue light's effects on health, we found lots of evidence that color matters even more than brightness. And it turns out that timing matters, too: Blue light during the day is great for your circadian rhythm. Blue light at night is not.

Sleep researchers have just begun studying the effects of night-time usage of laptops, cell phones, iPads and other devices that emit blue light. Evidence suggests that even just a little extra blue light at night can keep you awake later and negatively affect the quality of your sleep.

Our users say that f.lux prevents eyestrain. They also say that it's easier to wind down and go to sleep after using a f.lux-enabled device at night. Plus, you'll never glow blue in a restaurant again.

You can use f.lux because it makes you sleep better, or you could use it because it just makes you look better. Either way your eyes will thank you.

After installation: open Settings and tap f.lux. Choose your lighting type and transition speed (for older devices the long transition is instant to avoid flickering). By tapping each lighting option you can see a short preview of how your screen will look like after sunset.

If your screen appears orange, open settings and select a different lighting type. f.lux should make your phone look just like a book under your room lighting.

f.lux should have a minor impact on your battery life. f.lux itself uses less than 2 seconds of CPU each day.

f.lux only looks for your location when you run the app. Also, we don't record or track where you are - there's no server on our end.

The current version of f.lux requires Location Services to be enabled. If you install it with Location Services off, you should enable it in the settings.

iPhone 3g support is experimental and may slightly shift your colors during daytime. If you don't like the shift, uninstall f.lux and reboot your phone to restore to normal colors.

You can turn f.lux off at any time by choosing "Off" under the Enabled option in f.lux settings.

To contact us with questions or report a problem, please tap the Author link at the top of the page.

iOS 9.x stable. Allow install on 9.x, also location fixes. Allow install on 8.4. Fix sliders on 8.3. Minor UI update to support iOS7-style skin. Allow install on 8.3. Allow install on 8.2, add 1900K. Avoiding automatic cleanup. Disables "reduce white point" when f.lux starts to avoid visual glitches on A7. (Turning the feature back on will show the bug.) Avoiding iCloud drive conflicts Made preferenceloader work again Fixed "colors stay during daytime" case again. Nicer recovery in low-memory conditions. Force reboot on install to clear existing color problems. Daemon was killed by iOS in low-memory conditions. Restores connection to screen on failure. Full reboot on uninstall to restore factory color profile. Added 64-bit slice for A7 Fixed unlock detection to handle some more cases (i.e. this uses less battery) Disabled warm dimming - too broken. f.lux now sleeps when the screen is off (better for battery). New warm dimming, so in a dark room your screen can get even warmer. Also, fix an uninstall bug from 0.986 (uninstall + reboot + reinstall always works). Support for iOS7. Provides better defaults when CoreLocation fails (puts you at the equator). Fixes location failure after reboot/respring. Disables long transition on iPad 4. Uses less CPU (up to 80% less) in background. Resized for iPhone 5, UI rotation fixes. Fixed a leak, oops. Added an app to support iOS 5, now with sliders. CoreLocation is now off to save battery. Added daytime settings, some 3g fixes. Fixed a small memory leak. Recommended update. First public release. Added support for iPhone 3g. First release for testing.