Twilight: Blue light filter

Are you struggling to fall asleep at night? Do your children seem overly energetic after using tablets before bedtime? If you find yourself using smartphones or tablets in the evening, or if you're sensitive to light during migraines, the Twilight app might be the solution you need!

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

The Twilight app adapts 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 adjusts smoothly based on your local sunrise and sunset times. Twilight is also available for your Wear OS device, syncing the filter settings with your phone.

Documentation

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

Get More from Twilight

1. Bed Reading: Twilight makes night reading more comfortable on the eyes, allowing the screen backlight to be dimmed far beyond the standard settings.
2. AMOLED Screens: Twilight has been tested on AMOLED screens for five years without signs of depletion or over-burning. When properly configured, it reduces light emission and provides a more even light distribution, potentially extending the life of your AMOLED screen.

Basics on Circadian Rhythm and the Role of Melatonin

For further reading on the science behind Twilight, 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

• Location: To determine your local sunset and sunrise times.
• Running Apps: To disable Twilight in specific apps.
• Write Settings: To adjust the screen's backlight.
• Network: To access smart lighting systems like Philips HUE, helping to reduce blue light exposure in your home.

Accessibility Service

To filter notifications and the lock screen, Twilight may request the use of its Accessibility Service. Rest assured, this service is used only to enhance screen filtering and does not collect any personal data. Learn more about privacy concerns 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, and you can control the filtering from a "Wear OS Tile".

Automation (Tasker or Other)

For automation options, visit 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, & 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

Twilight: Blue light filter Screenshots