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

Recent studies indicate that exposure to blue light 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 Melatonin production, a hormone crucial for maintaining healthy sleep-wake cycles. Research has shown that using a tablet or smartphone for a few 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 filter's intensity smoothly adjusts according to your local sunrise and sunset times. Twilight is also available for your Wear OS device.

For more information, check out the documentation at http://twilight.urbandroid.org/doc/.

Get more from Twilight:

1) Bed reading: Twilight makes night reading more comfortable on the eyes, with the ability to dim the screen's backlight far beyond the standard controls.

2) AMOLED screens: Twilight has been tested on AMOLED screens for 5 years without any signs of depletion or over-burning. When properly configured, it reduces light emission and provides a more even light distribution, which may extend the life of your AMOLED screen.

Learn more about circadian rhythms and the role of melatonin at:

• 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 required by Twilight include:

• Location - to determine your local sunset and sunrise times.
• Running apps - to disable Twilight in selected apps.
• Write settings - to adjust the backlight.
• Network - to access smart lighting (Philips HUE) to reduce blue light in your home environment.

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

Twilight also syncs with your Wear OS device, allowing you to control the filter settings from a "Wear OS Tile".

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

Related scientific research includes:

• 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