Blocks blue light, eases eye strain, promotes better sleep

Struggling to fall asleep? Do your children get restless after using tablets before bed?

Do you use your smartphone or tablet late at night? Sensitive to light during migraines?

Twilight could be your answer!

Recent studies show blue light exposure before bed disrupts your natural (circadian) rhythm, making it harder to fall asleep.

The culprit is Melanopsin, a photoreceptor in your eyes sensitive to blue light in the 460-480nm range, which suppresses Melatonin, the hormone that regulates sleep-wake cycles.

Research indicates that using a tablet or smartphone for a few hours before bed can delay sleep by about an hour. See references below.

The Twilight app adjusts your device’s screen to the time of day, filtering blue light after sunset with a gentle red overlay. The filter strength adapts smoothly to your local sunset and sunrise times.

Twilight is also available for Wear OS devices.

Documentation

http://twilight.urbandroid.org/doc/

Get more from Twilight

1) Night reading: Twilight enhances comfort for evening reading by lowering screen backlight beyond standard controls.

2) AMOLED screens: Tested for 5 years on AMOLED displays, Twilight reduces light emission through dimming and evens light distribution by tinting dark areas, potentially extending screen 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 your local sunset/sunrise times

- running apps - to disable Twilight in specific apps

- write settings - to adjust backlight

- network - to control smart lighting (Philips HUE) and reduce blue light exposure

Accessibility Service

To filter notifications and lock screens, Twilight may request activation of its Accessibility Service. This is used solely to enhance screen filtering and collects no 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, controllable via 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 Circadian Rhythms after Gradual Sleep and Light Exposure Advances in Humans, Derk-Jan Dijk & Co, 2012

Room Light Exposure Before Bedtime Delays Melatonin Onset and Shortens Duration in Humans, Joshua J. Gooley, Kyle Chamberlain, Kurt A. Smith & Co, 2011

Light’s Effect on Human Circadian Physiology, Jeanne F. Duffy, Charles A. Czeisler, 2009

Single Sequence of Intermittent Bright Light Pulses Delays Circadian Phase in Humans, Claude Gronfier, Kenneth P. Wright & Co, 2009

Melatonin and Sleep Phase Relationships Influenced by Intrinsic Period and Light Intensity in Humans, Kenneth P. Wright, Claude Gronfier & Co, 2009

Sleep Timing and Bright Light Exposure Impact on Attentional Impairment During Night Work, Nayantara Santhi & Co, 2008

Short-Wavelength Light Sensitivity in Circadian, Pupillary, and Visual Awareness in Humans Without an Outer Retina, Farhan H. Zaidi & Co, 2007