Having trouble falling asleep? Are your children hyperactive when they play with the tablet before bed?
Do you use your smartphone or tablet at the end of the evening? Twilight may be the solution for you!
Recent research suggests that exposure to blue light before sleep can distort your natural (circadian) rhythm and lead to an 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 that can suppress the production of melatonin – a hormone responsible for your healthy sleep-wake cycles.
In experimental scientific studies, it has been shown that an average person reading on a tablet or smartphone for a few hours before bedtime can find their sleep delayed by about an hour. See references below.
The Twilight app allows your device screen to adjust to the time of day. It filters the blue light stream emitted by your phone or tablet after sunset and protects your eyes with a soft and pleasant red filter. The intensity of the filter is smoothly adjusted to the solar cycle based on your local sunset and sunrise times.
Documentation
Get more from Twilight
1) Reading in bed: Twilight is more pleasing to the eyes for reading at night. Especially since it is able to dim the screen backlighting well below the capacity of the backlight controls on your screen.
2) AMOLED displays: We tested Twilight on an AMOLED display for 5 years without any signs of burnout or over-burn. If configured correctly, Twilight causes less light emission (by enabling dimming) with a more even light distribution (dark areas of the screen such as the status bar are tinted). It can actually increase the lifespan of your AMOLED display.
Basics of 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 know your current bedtime / surise times
– running apps – to stop Twilight in selected apps
– write parameters – to adjust the backlight
– network – smartlight access (Philips HUE) to protect your home light from blue
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 progressive progression of sleep and light exposure in humans Derk-Jan Dijk, & Co 2012
Exposure to ambient light before bedtime suppresses the onset of melatonin and shortens the duration of melatonin 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 light pulses to delay the 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 Attention Disorders During Night Work Nayantara Santhi & Co 2008
Short-wavelength light sensitivity of circadian, pupil and visual consciousness in humans lacking an external retina Farhan H. Zaidi & Co, 2007
High sensitivity of the circadian rhythm of human melatonin to reset by short wavelength light. Lockley SW & Co. 2003
Sensitivity of the human circadian pacemaker to night light: Jamie M Zeitzer, Derk-Jan Dijk & Co 2000
