DownloadFilters blue light from your screen to reduce eye strain and support better sleep
Do you struggle to fall asleep? Are your kids too energetic after using a tablet before bedtime?
Do you use your smartphone or tablet late at night? Do bright screens bother you during a migraine?
Twilight could be your answer!
Recent studies indicate that blue light exposure before bed can disrupt your natural circadian rhythm and make it harder to fall asleep.
This happens because of a photoreceptor in your eyes called Melanopsin. It is sensitive to blue light in the 460–480nm range, which can suppress melatonin—the hormone that regulates healthy sleep-wake cycles.
Scientific experiments show that using a tablet or smartphone for several hours before bed can delay sleep by about an hour for the average person. See references below.
Twilight adjusts your screen to the time of day. After sunset, it filters blue light from your device and applies a gentle red tint to ease eye strain. The filter strength adjusts automatically based on local sunrise and sunset times.
Twilight is also available on Wear OS.
Documentation
http://twilight.urbandroid.org/doc/
Get More from Twilight
1) Bedtime Reading: Twilight creates a more comfortable viewing experience for reading at night. It can dim your screen brightness beyond the standard system settings.
2) AMOLED Screens: After five years of testing on AMOLED displays, Twilight shows no signs of screen burn-in. When set up correctly, it reduces overall brightness and evens out light distribution, which may help extend your screen's lifespan.
Basics on Circadian Rhythm and Melatonin
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
- Location – to determine local sunrise and sunset times
- Running apps – to pause Twilight in certain apps
- Write settings – to adjust screen backlight
- Network – to control Philips HUE smart lights and filter household blue light
Accessibility Service
To apply filtering to notifications and the lock screen, Twilight may request access to the Accessibility Service. This service is used only for screen filtering and does not collect personal data. Learn more at: 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. You can manage filtering directly from a Wear OS Tile.
Automation (Tasker or other)
https://sites.google.com/site/twilight4android/automation
Related Scientific Research
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 et al., 2012
Exposure to Room Light before Bedtime Suppresses Melatonin Onset and Shortens Melatonin Duration in Humans – Joshua J. Gooley, Kyle Chamberlain, Kurt A. Smith et al., 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 et al., 2009
Intrinsic period and light intensity determine the phase relationship between melatonin and sleep in humans – Kenneth P. Wright, Claude Gronfier et al., 2009
The Impact of Sleep Timing and Bright Light Exposure on Attentional Impairment during Night Work – Nayantara Santhi et al., 2008
Short-Wavelength Light Sensitivity of Circadian, Pupillary, and Visual Awareness in Humans Lacking an Outer Retina – Farhan H. Zaidi et al., 2007
