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F.lux logo.svg
Two photos of a screen affected by f.lux's default settings (on the right) and disabled (on the left), stitched together
Two photos of a screen affected by f.lux's default settings (on the right) and disabled (on the left), stitched together
Original author(s) Michael Herf, Lorna Herf
Developer(s) Flux Software LLC
Initial release February 2009; 9 years ago (2009-02)
Stable release
Windows: v4.76
macOS: 39.983
iOS: 0.9986[1]
Operating system Windows, macOS, Linux, Android, iOS
Available in English
License Freeware
Website justgetflux.com

f.lux is a cross-platform computer program that adjusts a display's color temperature according to location and time of day, offering functional respite for the eyes. The program is designed to reduce eye strain during night-time use, helping to reduce disruption of sleep patterns.[2][3]


The program is available for Microsoft Windows, macOS and Linux. It is also available for iOS devices, although it requires the device to be jailbroken.[4] Apple has not allowed the application in its App Store, due to its use of restricted developer tools.[5] The developer briefly hosted an Xcode project on GitHub, allowing iOS 9 users to sideload the application onto their devices, but retracted it at the request of Apple.[6] Following Apple's announcement of a similar function, called Night Shift, in iOS 9.3, the developer has called upon Apple to provide developer tools and to allow their application into the App Store.[7] A preview version for Android is available.[8]


Photo depicting the "darkroom mode".

Upon installation, the user can choose a location based on geographic coordinates, a ZIP code or the name of a location. The program then automatically calibrates the device display's colour temperature to account for time of day, based on sunrise and sunset at the chosen location. At sunset, it will gradually change the colour temperature to a warmer colour and restore the original colour at sunrise.[2][3]

f.lux offers a variety of colour profiles and pre-defined temperature values, modifying program behaviour for specific programs or activities; including a mode for film watching, decreasing red tinge (for 2.5 hours), and a darkroom mode that does not affect night-adapted vision.[2][3] Times can be inverted on f.lux for PC to provide warm lighting during the daytime (for people who work at night).[9] The program can control Philips Hue LED lighting, so that the color temperature of house lights follows f.lux's settings.[10]


f.lux proponents hypothesise that altering the colour temperature of a display to reduce the prominence of white–blue light at night will improve the effectiveness of sleep. Reducing exposure to blue light at night time has been linked to increased melatonin secretion.[11] Although the developer provides a list of relevant research on their website, the program itself has not been scientifically tested to determine its efficacy. In spite of this, f.lux has been widely and positively reviewed by technology journalists, bloggers, and users.[2][3][4]

See also[edit]


  1. ^ "f.lux for iOS". f.lux. Retrieved October 13, 2018.
  2. ^ a b c d Zukerman, Erez (October 31, 2013). "Review: f.lux makes your computer usable at night". PC World. Retrieved 3 March 2015.
  3. ^ a b c d Tanous, Jim (October 15, 2014). "Save Your Eyes and Improve Your Sleep with f.lux for OS X and Windows". TekRevue. Retrieved January 15, 2016.
  4. ^ a b Hoffman, Chris (October 23, 2014). "Reduce Eye Strain and Get Better Sleep by Using f.lux on Your Computer". How-To Geek. Retrieved January 15, 2016.
  5. ^ Hern, Alex (January 12, 2016). "Apple promises a good night's sleep with new iPhone feature". The Guardian. Retrieved January 20, 2016.
  6. ^ Tepper, Fitz (November 12, 2015). "F.uxd: Apple Says Screen Brightness App Violates Developer Agreement". TechCrunch. Retrieved January 15, 2016.
  7. ^ Perez, Sarah (January 15, 2016). "F.lux Asks Apple To Let Its Screen Color Adjustment App Back Into App Store". TechCrunch. Retrieved January 20, 2016.
  8. ^ "f.lux Home Page". f.lux. Retrieved September 21, 2016.
  9. ^ "f.lux: F.A.Q. - I work nights. How do I flip the day and night settings?". justgetflux.com. Retrieved 31 October 2016.
  10. ^ "f.lux has been updated to a new version". justgetflux.com. Retrieved 31 October 2016.
  11. ^ Takeshi, Morita; Hiromi, Tokura (1996). "Effects of Lights of Different Colour Temperature on the Nocturnal Changes in Core Temperature and Melatonin in Humans". Journal of Physiological Anthropology. 15 (5): 243–6. PMID 8979406.

External links[edit]