Best answer: Blue light filtering screen protectors use a special coating that blocks light in the 380-500 nanometer range. Electronics like phones use LED or OLED panels that emit light in this range to help brightness and improve clarity, but it can also reach the rear of the retina. Some studies claim this can be harmful, but so far there is no conclusive proof to this. What scientists and doctors do agree on, though, is that blue light can make it harder for us to get to sleep. To help with that, you'll need a proper screen protector.
Amazon: Samsung Galaxy Anti-Glare Screen Protector (opens in new tab) ($16)
What is Blue Light?
There are two types of "Blue Light" you'll hear mentioned when talking about electronics: ultraviolet light and visible blue light.
Light waves are measured in nanometers, and the human eye can typically see light between about 380 and 750nm. Light lower than 400nm is known as Ultraviolet or UV light and can be harmful to the human eye. We can't see most of this light (light in the range of 350-400nm is sometimes called **near-UV ** light) but many sources do emit it. The most well-known source of UV light is the sun; if you've ever had a sunburn you've experienced an overexposure to UV light. With enough exposure, the same can happen to our eyes. This is why welders have to wear goggles or a mask.
Almost every piece of electronics you own has mechanisms to block harmful UV rays. But the other type of blue light — the visible and sometimes irritating light between 380 and 500nm — isn't treated the same way. There are two reasons why: it's not proven to be directly harmful to humans, and at the right intensity, we see this as a whitish light that makes our displays look brighter and crisper. While blue light might not be harmful to our eyes, it does have an effect that most experts agree upon: it can increase alertness and make it difficult to fall asleep.
Do you need help?
Not everyone experiences restlessness or difficulty falling asleep from blue light, but if you do, you understand how tough it can be to get to sleep right after a long session in front of a display. Phone makers are now including a special screen mode that omits much of the light in the 380-500nm spectrum. If you've used a phone with this feature you know how "orange" the screen can appear in this mode and understand why blue light is desirable during the daytime!
If your phone doesn't include a blue light filtering mode, you totally should invest in a blue light filtering screen protector. Likewise, if you really don't like the orange hue blue light blocking display modes tend to exhibit, a blue light filtering screen protector can alleviate much of the eyestrain and alertness without making the screen quite so orange.
Blocks what you don't want
Block both Ultraviolet light and "blue light" with this curved 3D tempered glass screen protector. Available for the Galaxy Note 8, Galaxy Note 9, Galaxy S8 and S8+, Galaxy S9 and S9+.
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