Twilight: Blue light filter

Are you struggling to fall asleep? Do your kids become hyperactive after playing with their tablet before bedtime? If you're using your smartphone or tablet in the evening or are sensitive to light during migraines, Twilight might be the solution you need!

Recent research indicates that exposure to blue light before sleep can disrupt your natural circadian rhythm, making it difficult to fall asleep. This is due to the photoreceptor in your eyes, Melanopsin, which is sensitive to blue light in the 460-480nm range. Such exposure can suppress Melatonin production, a hormone crucial for maintaining healthy sleep-wake cycles. Studies have shown that reading on a tablet or smartphone for a couple of hours before bed can delay sleep by about an hour.

The Twilight app adjusts your device's screen to the time of day, filtering out blue light after sunset and applying a soothing red filter to protect your eyes. The intensity of the filter smoothly adjusts according to your local sunset and sunrise times, ensuring a comfortable viewing experience.

Twilight is also compatible with Wear OS devices, enhancing its utility across your tech ecosystem.

Documentation

Learn more about Twilight at http://twilight.urbandroid.org/doc/.

Get More from Twilight

1) Bed Reading: Twilight offers a more eye-friendly experience for night reading, capable of dimming the screen beyond the usual backlight controls.

2) AMOLED Screens: Extensive testing on AMOLED screens over five years shows no signs of depletion or over-burning. Properly configured, Twilight emits less light and distributes it more evenly, potentially extending your screen's lifespan.

Basics on Circadian Rhythm and the Role of Melatonin

For further reading on circadian rhythms and Melatonin, visit:

• http://en.wikipedia.org/wiki/Melatonin
• http://en.wikipedia.org/wiki/Melanopsin
• http://en.wikipedia.org/wiki/Circadian_rhythms
• http://en.wikipedia.org/wiki/Circadian_rhythm_disorder

Permissions

Twilight requires the following permissions:

• Location - to determine your local sunset and sunrise times.
• Running Apps - to pause Twilight in selected applications.
• Write Settings - to adjust the screen's backlight.
• Network - to connect with smart lighting systems like Philips HUE, helping to filter blue light in your home environment.

Accessibility Service

To filter notifications and the lock screen, Twilight may request the use of its Accessibility Service. This service is used solely to enhance screen filtering and does not collect any personal information. For more details, visit https://twilight.urbandroid.org/is-twilights-accessibility-service-a-thread-to-my-privacy/.

Wear OS

Twilight syncs your Wear OS screen with your phone's filter settings, and you can control the filtering via a "Wear OS Tile".

Automation (Tasker or Other)

For automation options, check out https://sites.google.com/site/twilight4android/automation.

Related Scientific Research

Explore the scientific foundation behind Twilight's effectiveness:

• Amplitude Reduction and Phase Shifts of Melatonin, Cortisol and Other Circadian Rhythms after a Gradual Advance of Sleep and Light Exposure in Humans - Derk-Jan Dijk, & Co 2012
• Exposure to Room Light before Bedtime Suppresses Melatonin Onset and Shortens Melatonin Duration in Humans - Joshua J. Gooley, Kyle Chamberlain, Kurt A. Smith & Co, 2011
• Effect of Light on Human Circadian Physiology - Jeanne F. Duffy, Charles A. Czeisler 2009
• Efficacy of a single sequence of intermittent bright light pulses for delaying circadian phase in humans - Claude Gronfier, Kenneth P. Wright, & Co 2009
• Intrinsic period and light intensity determine the phase relationship between melatonin and sleep in humans - Kenneth P. Wright, Claude Gronfier & Co 2009
• The Impact of Sleep Timing and Bright Light Exposure on Attentional Impairment during Night Work - Nayantara Santhi & Co 2008
• Short-Wavelength Light Sensitivity of Circadian, Pupillary, and Visual Awareness in Humans Lacking an Outer Retina - Farhan H. Zaidi & Co, 2007