Unfortunately this research paper mentioned above by name is not free, but its abstract is. I hope you click and read the abstract.
For persons not familiar with this kind of scientific conversation at all, many items mentioned in this abstract must be a mystery.
So let's tackle just only one mystery mentioned in this abstract's conclusion: that is, the trouble with looking at a computer screen in the evening IS NOT BECAUSE IT IS BRIGHT, but rather because it emits a certain LIGHT WAVELENGTH.
The phrase light wavelength is just a very accurate and scientific way to say light color.
But, don't computer screens emit all colors, not just one? And, is there a color of light you should not look at during the evening time?
Let's answer the last question first, with a yes.
Your eye and brain recognize the blue sky light as a sign that it is daytime. Even with cloud cover, that day time blue sky light gets mixed up with the whiteness of the clouds and your eye and brain still know that that "whiteness" is not pure white, but rather has some blue added to it.
So any light color with blue-ness added, tells the brain that it is more likely day than night time. So in the evening if you want your body and brain to cooperate and operate with the night schedule as God designed it to, you should avoid light emitting sources that have the color blue added into their emission.
Which brings us back to the first question, doesn't a computer screen emit all colors so why is it being blamed for emitting too much of one color "wavelength"?
The truth is that a computer screen does not and cannot emit violet or cyan or yellow or orange light at all. What a computer screen does is emit mixed amounts of blue and green and red light in such a manner that it tricks your eye into interpreting those mixtures of blue, green and red as those other missing colors.
Also, a computer screen brightens all colors by adding some blue light into the mix even though it is not needed to trick the eye into seeing some color.
This means that regardless of what color light you think your computer screen is emitting, it is always emitting some blue light, even when the blue pixels are completely turned off, because even the green pixels also emit some blue light to help brighten them up.
Therefore, I recommend that all persons watching TV or using a computer screen during the evening time wear orange lens eyewear to enhance and preserve their ability to focus their attention and concentration for the day-time challenges life throws our way.
Our orange lens eyewear allows no blue light to pass though.
