The interesting thing about monitors is that they should be like the Sun.
The second interesting thing about monitors is that they should be like a lightbulb.
They failed at both of this…
Monitors are like the Sun. They emit all colors of the rainbow but as you can guess it’s probably not so normal to look at the Sun at night.
But unlike the Sun, monitors don’t emit full spectrum sunlight.
At the picture above you can see the light spectrum of the sun.
Notice how blue, green, yellow and red light are almost equal. We need this kind of ratio and this is embedded in our biology.
Yes, the Sun emits also UV light, but our body is attuned to UV light and produces important substances like Vitamin D when we get it from the Sun.
Direct UV light exposure to our eyes is also not so good, but UV light is stopped at the front of our retina while blue-violet light enters deep into our retina and may cause macular degeneration in the long run.
At the picture above you see the light specters of different light sources. The light emitted from the sun is like the first graphic while the light emitted from monitors is like the third graphic.
Notice how much blue light the LED lights emit and how little green light.
The problem is not actually the blue light, the problem is the ratio and that red light is almost missing from our monitors.
We can somehow fix this by reducing the color temperature of the screen, but the red light never becomes more and this is why we need more red light exposure.
If you read about this, red light is actually one of the most important lights. Science has proved that plants grow way bigger when they get a lot of red light and low amount of blue light.
In humans, blue light regulates our mood and it’s important also, but at night it stimulates our melanopsin photoreceptors in the eyes, our melatonin secretion stops and we can’t fall asleep if a lot of blue light is present around us.
The standard Incandescent Edison light bulbs are good at producing blue light, but they again fail in the morning when we need blue light to lift our mood.
The thing about sunlight is that not only it’s full spectrum light, but it also changes during the day and night. Well, there is actually no light at night, but still.
Our biology has evolved for millions of years to work together with this shift of light and we also need this change.
In our modern lifestyle, it’s best for us to try to replicate this gradual change with programs like Iris which tries to replicate the Sun spectrum change.
Monitors are like a light bulb. But instead of one light bulb, we have millions of them in the size of several inches.
In order to reduce their energy use and brightness, you need to turn them ON and OFF hundred of times per second.
And this thing, this ON and OFF thing is called flicker.
Our brain is slow and we do not perceive this, but our eyes are fast and our iris starts to open and close like this
Of course, the amplitude here is much bigger the show the effect since the flicker rate of the monitor is much faster but basically, our eye starts to contract like a muscle.
You can test this by turning the light in your room ON and OFF fast and take a video or look in the mirror.
The science behind this thing is that in dark we need more light and our pupil is dilated.
When there is a lot of light around us or there is lots of daylight our pupil is undilated.
This is how our eye controls the amount of light entering it.
You may be thinking why do the monitors need to turn ON and OFF and why they can’t just glow all the time, but it’s not that simple.
LED lights will use a lot of energy if they are constantly ON and they may also overheat. Same goes for other monitor types.
The bigger problem is actually that the lower the frequency of this flicker and the bigger the breaks between this 2 states, the more energy efficient the monitor is.
Energy efficiency sells. Better battery life sells and this is why manufacturers prefer to make low backlight frequency monitors.
This is why manufacturers use cheap and energy efficient methods like Pulse-width modulation to control the brightness of the monitor.
The problem is that the lower the frequency of this flicker the bigger are our iris contractions and the more we feel eye pain.
One of the best ways to fix this problem is to just use E-ink devices but they are slow for real-time images.
We need new kind of technology and new kind of monitors which change the colors fast without flicker and without excessive blue light.
Some flicker-free monitors actually still flicker but they flicker at a higher frequency which is better for the eyes.
The ideal flicker-free monitor has a constant voltage applied to the backlight.
Pulse Width Modulation (PWM) is a method to control the brightness of your monitor by settings the backlight ON and OFF at high frequency.
Our brain doesn’t perceive this, but we get a lot of eye strain and headaches from this.
If this done at the really high frequency it’s not so unhealthy, but the problem is that the lower the brightness of the monitor the lower is the frequency of the backlight.
This is just an introductory article and I’m not going to get into more details, but what you need to know is that at maximum hardware brightness from the monitor buttons there is no PWM and your eyes will hurt less.
LED monitors with PWM at minimum brightness in slow motion look like the video below
CCFL monitors with PWM at minimum brightness in slow motion look like the video below
You may think now then Why is PWM used and the answers are actually really straightforward.
PWM is really easy to implement in a hardware circuit. You only need to switch the backlight ON and OFF fast.
PWM gives a wide range of brightness and luminance reduction while flicker-free monitors are capped at certain minimums and maximums.
PWM is energy efficient and requires less battery life.
There are 2 good solutions to the PWM problem.
The first one is to buy a flicker-free monitor. Flicker-free monitors use something called DC dimming which doesn’t make the backlight to flicker but has a limited brightness reduction range.
Your second option is to use Iris which uses the video card to reduce the luminance of the screen. This changes the colors a bit, but for people who don’t need exact colors of the screen, it’s cheap and effective solution.
Now let’s look at both solutions at more details.
Flicker-free monitors use DC dimming and don’t flicker. The current going to the backlight looks like this
Since they don’t use PWM they also have limited brightness reduction range.
Flicker-free monitors are much more expensive since the DC dimming circuit is more expensive to implement.
They are also not as energy efficient as the PWM monitors, but they preserve the colors even at minimum brightness.
Iris is software which can reduce the brightness of all monitors without PWM and without changing the backlight flicker-frequency or the current through the backlight.
It does this by using the video card to move the white point of the monitor. This gives you really big brightness reduction range.
Iris can also gradually adjust your screen brightness depending on the time of the day so your screen will match the light around you at night.
Iris is a cheap and effective solution for reducing the negative effects of monitors with PWM flicker.
By controlling the brightness without PWM, Iris helps with eye strain, dry eyes and headaches caused by PWM flicker.
On some laptops with old Intel HD Graphics graphics card and drivers, you can also control the PWM flicker Hz of the backlight to make it higher and more healthy.
Iris has this feature called PWM control integrated but hidden by default since this can damage your monitor if you set the frequency too high.
1. Set your monitor Hardware brightness to 100% using your monitor buttons.
2. Use Iris to control the brightness without PWM
If you liked this article share it with friends. You can also try Iris, which is software for eye protection and better sleep.
Iris will automatically control your brightness depending on the time of the day and try to match it to the light around you. This will help you feel less eye pain when you use your computer.
The program also controls the brightness of your screen without using PWM. This will help you to use your computer for longer periods of time without feeling eye strain or headaches.