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.


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

- 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

Automation (Tasker or other)

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

From version Twilight: Blue light filter 13.5:

- Not filtered screenshots on all Android versions + better status and navbar coloring

(Android 2.2+)
Latest: 5.4 on December 18, 2015
(Android 2.3+)
Latest: 7.0 on January 12, 2017
(Android 4.0+)
Latest: 11 on November 29, 2019
(Android 4.1+)
Latest: 13.5 on June 5, 2023
Apps related to Twilight: Blue light filter


Uploaded:November 29, 2022 at 4:51PM UTC

File size:1.79 MB

All versions
Twilight: Blue light filter 13.5


Uploaded:June 5, 2023 at 2:54PM UTC

File size:7.45 MB


Twilight: Blue light filter 13.4


Uploaded:April 28, 2023 at 6:44AM UTC

File size:7.15 MB


Twilight: Blue light filter 13.3


Uploaded:December 22, 2022 at 4:46AM UTC

File size:7 MB


Twilight: Blue light filter 13.2


Uploaded:November 29, 2022 at 4:50PM UTC

File size:7 MB


Twilight: Blue light filter 13.1


Uploaded:September 29, 2022 at 6:02AM UTC

File size:6.99 MB


Twilight: Blue light filter 13.0


Uploaded:September 21, 2022 at 9:12AM UTC

File size:6.96 MB



Uploaded:May 17, 2022 at 9:31PM UTC

File size:6.78 MB


Twilight: Blue light filter 12.16


Uploaded:April 2, 2022 at 5:01AM UTC

File size:6.78 MB


Twilight: Blue light filter 12.15


Uploaded:February 24, 2022 at 8:30AM UTC

File size:6.77 MB


Twilight: Blue light filter 12.14


Uploaded:January 25, 2022 at 8:12AM UTC

File size:6.82 MB