The Science behind Blue Light
Visible light is a form of electromagnetic radiation. The wavelength of the light defines its
colour and also its associated energy. Longer wavelengths have low energy and are grouped as
warmer colours whereas shorter wavelengths have comparatively higher energy and are
grouped as cool colours. Blue light has a wavelength of around 400 – 470 nm and therefore has
more energy when compared to the warmer yellow – red colours of 600 – 700 nm. The colour
temperature that indicates the colour tones of light is generally measured in Kelvins (K). Colour
temperatures over 5000 K are called “cool colours” or bluish colours and the values between
2000 – 3000 K is called “warm colours” or yellowish colours.
Research shows that the penetration capability of the high energy beams into human tissues is
relatively high than their lower energy counterparts. This very concept is used in the X-ray
Photography as well. X rays that are high in energy than the blue light are so intense that they
pass through the soft human flesh easily. Bones and other hard tissues block most of the X rays.
A film captures the variations in these X rays as shadows of those tissues & bones. Medical
professionals study the internal structure of these objects with the help of these X ray
Why is Blue light harmful for eyes ?
Blue light has more energy can easily pass through the very sensitive cornea, the lens and
finally, almost all of it is reached to the retina of the eye. Colours like yellow, Red being less
intensive, will be blocked more by the lens of the eye before they reach the retina. This is why
warmer colours are generally pleasant for the eyes than the harsher cooler colours. This is true
even with the blue light emitted from laptop screens. A blue light filter for laptop screens like
CareUEyes can completely block this harmful blue light and render a pleasant warmer
A continuous exposure of blue light from a laptop screen for extended periods of time leads to a
number of complications like dry eyes, headaches, eye twitches etc all of which are collectively
grouped under an umbrella term as Computer Vision Syndrome (CVS). As our eye is not able
to efficiently block most of the blue light, a long-term cumulative and constant exposure to this
high energy radiation will result in the damage and slow death of the cells of the retina. This
will accelerate the age-related macular degeneration (AMD) and ultimately results in a
permanent vision loss.
Blue light and Circadian rhythm
Human circadian rhythms have evolved to depend on the sun. We tend to be more active during
daytime when a lot of blue light is around us. During nights, our brain secretes a sleep
hormone Melatonin as a response to the absence of blue light. This hormone is very essential
for a good night’s sleep. High energy blue light also plays a major role in defining our mood,
activity and also sleep quality.
This very dependence of blue light for the regulation of circadian rhythm has made our bodies
evolve a special photoreceptor Melanopsin in the eye which is very sensitive to blue light. Light
as a factor now is very essential not only to our sleep but it acts like a synchronizer for many
other associated biological processes including temperature regulation as well. When the levels
of Melatonin rises in our body, as a response the body lowers its temperature and prepares for a
sleep phase. When Melanopsin receives blue light during the day, it triggers a response in the
brain to stop Melatonin secretion and our bodies come back from the sleep mode and become
active again. In this way, our entire biological clock runs on the basis of light.
Exposure to the artificial blue light especially from laptop screens during nights confuses the
body and distorts the circadian rhythm and thereby causes inability to fall asleep. This is the
very reason why it is difficult for people who work on the computer screen at night to fall
asleep. A constant exposure to blue light during nights keeps our brain at a higher activity level
for extended periods of time. This eventually leads to increased exhaustion, lack of focus,
anxiety and other complications which ends up in a lowered productivity. When the laptop
screen emits only warmer lights at night, our brain functions at a comfortable rate without any
disruption in the circadian rhythm and thereby decreasing sleep deprivation rate despite late
How can CareUEyes help us ?
Most computer monitor displays are designed to emit light that has blue colours around 6500K.
Laptop screens are primarily designed to emit a lot of blue light to create a natural daylight
effect on the screen. In order to protect our eyes from these harsher blue lights especially during
nights, a blue light filter for laptop screens in very much needed. Some hardware devices like
tinted screen filters can be used. Though they filter out blue light and other UV light from the
laptop screens, they also distort the text & images on the screen causing other complications
like “digital eye strain”. Aspects like different screen sizes may need different sized filters to
ensure a proper fit, need for a separate screen filter for every screen, complexity & bulkiness in
the usage and handling turns this option to become an expensive and complex affair in the end.
Another best way is to not use the laptop screens at all during nights. This isn’t a viable option
for working professionals, programmers etc who have to work late in the nights. An alternative
solution is very much required to suit the requirements of everyone.
CareUEyes is a lightweight, software version of the blue light filter for laptop screens. It
primarily runs on Windows OS. It runs in the background and does two things simultaneously
to constantly protect our eyes.
- It masks or “filters” the harsh blue light emitted from a laptop screen by shifting the
colour tones to the warmer parts of the spectrum.
- It lowers the brightness of the screen by changing the gamma value of the screen.
When these two things combined with the hardware screen brightness control of the laptop, the
user can get a pleasant viewing experience based on the contents of the screen and the
Unlike the hardware screen filters, CareUEyes works on multiple monitors irrespective of
their sizes and configuration. One needn’t buy any hardware devices like tinted screen filters,
special tinted eyeglasses or anything else to protect their eyes from the harsher blue light
emitted from the screens. The user can now comfortably work for longer durations without
causing much strain to the eye and body.
Will CareUEyes damage my laptop ?
CareUEyes monitors the laptop screen constantly and shifts any blue light to its warmer
counterpart before it is emitted from the screen. It almost works at the graphics delivery level
by hooking to graphics rendering interfaces. Despite this constant monitoring, the amount of
CPU resources it consumes is almost negligible. Even memory consumption is also very little
compared to other alternative softwares. At most it consumes just under 5MB of working
memory of the system.
One need not be apprehensive about the working of CareUEyes. Though it works at the
graphics rendering level, it won’t in any way manipulate any of the systems / hardware settings
or change any configuration of the system. When the program is terminated, it cleanly exits and
restores all the natural and original colour schemes of the laptop screen.
Brightness feature of the program is equally important. The user can vary the slider between
20% to 100% brightness of the screen. The basic principle behind the change of brightness of
the screen is not at the hardware level but the program cleverly modifies the gamma value of
the screen in order to manipulate the resulting brightness and thus in no way affects the
hardware configuration of the monitor at all.
Unlike other methods that employ running a constant script to lower the brightness of the
screen, it just alters the final gamma output of the screen and the end result is a lower brightness
without any flickers/dots on the screen and a constant brightness spread across the monitor.
So CareUEyes will be well suited even for CRT & TFT monitors as well along with the modern
LCD / LED screen. It works equally well in programmatically controlling the gamma level of
the monitors irrespective of their inherent structural design or working.
All in all, CareUEyes filters the blue light and shifts the colour spectrum to warmer pleasant
yellow light, it reduces the brightness gamma of the screen and reduces eye strain so in the end,
during nights, as exposure to the blue light is reduced, it helps our brain to secrete Melatonin in
good quantities thereby helping us to sleep better. A uniform shift of colour tones and a uniform
brightness on the screen ensures a seamless experience to the end user. All of this is done by
consuming minimal computing resources ensuring no impact on the overall performance of the
system. The resource footprint of the software is also constantly maintained to be negligibly
More on the features of CareUEyes
CareUEyes has two sliders on the Display menu. One to change the colour temperature and the
other to programmatically change the brightness of the screen. The user can also assign hotkeys
to both these functions to simultaneously change them on the fly. This very feature separates
CareUEyes from other software solutions. It just sits in the tray while running in the
background, a single click on the tray icon activates the sliders screen. The user can now vary
both the colour temperature and the brightness on the fly with just a couple of more clicks.
It has 8 preset modes like Office, Reading, Editing etc that suits to various purposes. Editing
mode is very useful for programmers who wish to work late in the nights. The mode basically
inverts the colours on the screen thereby stripping out the bright colour tones completely. Other
modes give a quick combination of temperature and brightness values depending on the
Hotkey for colour temperature changes the value by 55K and the brightness hotkey changes the
brightness of the screen by 4% for every keystroke.
Just by changing the slider the user can reduce the colour tones to as low as 1000 K and can
increase to the natural 6500 K of the laptop screen. CareUEyes is capable of handling this wide
range of 1000K – 6500K colour temperatures with ease.
A disable hotkey is also included to manually pause the CareUEyes working and restore the
original screen colours with the stroke of a hotkey. This is essentially useful for designers /
photographers/ artists who want accuracy of colours when they intend to use certain specialized
softwares. Rules can also be specified in the inbuilt rules manager to direct the working of
CareUEyes depending on the foreground software. When CareUEyes detects a whitelisted
software that is currently focussed / brought into the foreground / activated, it automatically
disables its working and the screen will have original colours till the software goes into the
The user still should have access to the hardware brightness control of the laptop screen to have
a complete and efficient control over the overall viewing experience depending on the ambient
It is recommended to change the colour temperature of the laptop screen to warmer values
when working late in the nights to prevent any distortions in the circadian rhythm / secretion
levels of Melatonin. If the user also sets a correct brightness level depending on the ambient
light, strain on the eye will be largely reduced thereby enabling the user to work for longer
The brightness value should be set such that the light from the screen matches with the ambient
/ indoor lighting. If the user works in a dark room with no ambient light, It is recommended to
set the brightness value to 20% and lower the laptop hardware brightness value to the
minimum. In other words, A laptop screen shouldn’t be the only source of light in the room.
Proper ambient light is equally important to reduce eye strain.
The very purpose of this article is to make one realize the harmful and cumulative effects of a
constant artificial blue light exposure particularly at nights from the laptop screens. In this era
of modernization, when computer screens have become an inseparable part of our life, an
efficient and a light weight blue light filter for laptop screens like CareUEyes, that can change
the colour temperature and the brightness, without compromising the systems resources, is a
great gift we give to our most precious eyes and to our overall wellbeing.