Twilight: Blue light filter

4.6
407K reviews
10M+
Downloads
Editors' Choice
Content rating
Everyone
Screenshot image
Screenshot image
Screenshot image
Screenshot image
Screenshot image
Screenshot image
Screenshot image
Screenshot image
Screenshot image
Screenshot image
Screenshot image

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? 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.


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/

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

High sensitivity of the human circadian melatonin rhythm to resetting by short wavelength light. Lockley SW & Co. 2003

Sensitivity of the human circadian pacemaker to nocturnal light: Jamie M Zeitzer, Derk-Jan Dijk & Co 2000
Updated on
Jun 1, 2022

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
4.6
407K reviews
Nicole theTrainer
June 11, 2022
I have used Twighlight for several years and it's been so helpful reducing eye strain and dimming my phone further than the factory had set. This was especially helpful during hours of reading when my eyes really needed it. I have maintained good vision with the aid of using this app. I have never once disliked Twighlight. There have been improvements made over the years, and a recent update added the function to take a screenshot without pausing the filter. ⭐⭐⭐⭐⭐ Quality
5 people found this review helpful
Did you find this helpful?
Ash Pierce
May 20, 2022
Been using Twilight for 3-4 years. Seriously cuts down on eye strain in the evening, and allows me to use my phone in the evening without worrying about messing with my sleep cycles. I like that I can set a timer, so I don't need to remember to turn off on/off. Only complaint is that it displays over my camera, so any photos you take with the filter enabled will have a red tint. But it's easy to switch it off for a quick second to take a picture , so it's not a big deal.
23 people found this review helpful
Did you find this helpful?
Urbandroid (Petr Nálevka)
May 20, 2022
Hello Ash, the app does not alter the photo files - the filter is applied only on the screen. If you pause the filter and check the photos without the filter being currently present on the screen, the colors should be normal. For more details, please contact support@urbandroid.org. Thank you.
Samuel Triplett
May 20, 2022
This such an eye saver. This, f.lux, and dark mode whenever possible are such a nice suite of utilities for doing anything on a screen at night. I'm impressed with all the possible customization. 3 ways to augment my phone's light output and 4 ways to schedule when Twilight is activated is more than I would have expected. It's a quiet, hands-off app made for one thing and it does it well.
6 people found this review helpful
Did you find this helpful?

What's new

- Fix for a regression - the quick setting dialog not being filtered
- Better Stop option on Android TV