Twilight: Blue light filter

Are you struggling to fall asleep at night? Do your kids become hyperactive after using tablets before bedtime? If you're sensitive to light, especially during migraines, or if you use your smartphone or tablet late into the evening, 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 harder to fall asleep. This is due to a photoreceptor in your eyes called Melanopsin, which is sensitive to blue light in the 460-480nm range. This light can suppress the production of Melatonin, the 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.

Twilight is an app designed to adapt your device's screen to the time of day. It filters out blue light from your phone or tablet after sunset, using a soft and pleasant red filter. The intensity of this filter smoothly adjusts based on your local sunset and sunrise times, protecting your eyes and helping you maintain a healthier sleep schedule. Twilight is also compatible with Wear OS devices.

For more information, visit the Twilight documentation.

Get more from Twilight:

1. Bed Reading: Twilight makes night reading more comfortable for your eyes, allowing you to dim the screen far below what's possible with standard backlight controls.

2. AMOLED Screens: Extensive testing on AMOLED screens over 5 years shows no signs of depletion or over-burning. Properly configured, Twilight reduces light emission and promotes even light distribution, potentially extending your AMOLED screen's lifespan.

Basics on Circadian Rhythm and Melatonin:

• Melatonin
• Melanopsin
• Circadian Rhythms
• Circadian Rhythm Disorder

Permissions:

• Location: To determine your current sunset and sunrise times.
• Running Apps: To disable Twilight in selected apps.
• Write Settings: To adjust the screen backlight.
• Network: To access smart lighting systems like Philips HUE to filter blue light in your household.

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. Learn more at Twilight's Accessibility Service.

Wear OS:

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

Automation (Tasker or other):

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