Twilight: Blue light filter

4.6
429K reviews
10M+
Downloads
Editors' choice
Content rating
Everyone
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About this app

Are you having trouble falling asleep? Are your kids hyperactive when playing with the tablet before bed time?
Are you using your smart phone or tablet in the late evening? Are you sensitive to light during migraine?
Twilight may be a solution for you!

Recent research suggests that exposure to blue light before sleep may distort your natural (circadian) rhythm and cause inability to fall asleep.

The cause is the photoreceptor in your eyes, called Melanopsin. This receptor is sensitive to a narrow band of blue light in the 460-480nm range which may suppress Melatonin production - a hormone responsible for your healthy sleep-wake cycles.

In experimental scientific studies it has been shown an average person reading on a tablet or smart phone for a couple of hours before bed time may find their sleep delayed by about an hour. See references below..

The Twilight app makes your device screen adapt to the time of the day. It filters the flux of blue light emitted by your phone or tablet after sunset and protects your eyes with a soft and pleasant red filter. The filter intensity is smoothly adjusted to the sun cycle based on your local sunset and sunrise times.

You can also use Twilight on your Wear OS device.

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

Get more from Twilight
1) Bed reading: Twilight is more pleasant on the eyes for night reading. Especially as it is able to lower the screen backlight far below the ability of the backligt controls on your screen

2) AMOLED screens: We have tested Twilight on an AMOLED screen for 5 years without any sign of depletion or over-burning. If properly configured Twilight causes less light emission (by enabling dimming) with more equal light distribution (dark areas of the screen such as the status bar get tinted). This may in fact increase your AMOLED screen life time.

Basics on circadian rhythm and the role of 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 find out your current sunset/surise times
- running apps - to stop Twilight in selected apps
- write settings - to set back-light
- network - access smartlight (Philips HUE) to shield you household light from blue

Accessibility Service

In order to filter also your notifications and lock screen the app may ask for enabling Twilight Accessibility Service. The app uses this service only to better filter your screen and does not collect any personal information. Please read more about this at https://twilight.urbandroid.org/is-twilights-accessibility-service-a-thread-to-my-privacy/

Wear OS

Twilight also syncs your Wear OS screen with your phone's filter settings. You can control filtering 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, & 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
Updated on
30 Aug 2024

Data safety

Safety starts with understanding how developers collect and share your data. Data privacy and security practices may vary based on your use, region and age. The developer provided this information and may update it over time.
No data shared with third parties
Learn more about how developers declare sharing
No data collected
Learn more about how developers declare collection

Ratings and reviews

4.6
400K reviews
Teddy J
10 November 2024
Phenomenal app. It's easy to use, reliable, and wonderfully flexible. The quick-settings tile is amazing - for years and years I've had it set up so Twilight is on the first page for easy access whenever I open up the notification tray. I love that I can long-press it to open up the app too. No ads, too! I can't praise it enough for the years of good, straightforward utility it's provided me.
7 people found this review helpful
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Jonathan Hicks
8 November 2024
This one actually works! I've tried four or five other dimmer apps. Some of them had the dimming temperature wrong, some of them had a "flashlight" button next to the "dim" button, causing you to blind your partner while you sleep, some of them just didn't work without messing with disability settings! This one worked out of the box with minimal tinkering, has a VERY workable user interface, and doesn't turn my flashlight on when I want to dim my screen. I don't write reviews but this was worth!
6 people found this review helpful
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Wyatt McGhee
9 September 2024
Excellent app for filtering blue light at night; screen is much easier on the eyes. You can customize the hours or set from sunset to sunrise, BUT the "schedule profile" function is confusing. I wish the slidebar was not the only way to set custom times! It would also be helpful if there was an on/off feature to more easily tell if app is currently on or off.
11 people found this review helpful
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Petr Nálevka (Urbandroid)
25 September 2024
Hello Wyatt, sorry for the late reply - you can tap the cog icon in the custom mode, and it will open a time picker. On this time picker, you can choose the sunrise and sunset. Or tap the keyboard icon in the time picker to enter the times manually. For more details, please contact [email protected]. Thank you.

What's new

- Fix for Alarm permission flickering
- Material 3 redesign
- Multi display support
- Targeting Android 14
- Preview slider changes even when filter is not active
- Profile color indicator