As the time we spend in front of screens has increased, so has our exposure to the LED blue light emanating from devices like laptops, tablets and mobile phones.

There’s concern that too much exposure to blue light can have an impact on the eyes. Although electronic devices emit some LED blue light, the main source of blue light (including blue-violet light) is sunlight, even indoors. Even so, blue light glasses that claim to increase visual comfort have rapidly risen in popularity.

Researchers are still determining how much blue light impacts the eyes, particularly LED blue light emanating from digital screens. Because this information isn’t yet conclusive, some marketing claims seem a little suspect, leading many consumers to wonder if blue light filtering glasses really work.

To determine if these glasses are right for you, read on for more information about blue light’s currently known effects and exactly how the best blue light filtering glasses work.

Should I be concerned about blue light?

Blue light is part of the visible light spectrum, with wavelengths ranging from about 400 nanometers (nm) to 500 nm. It can be further separated into blue-violet light (about 400 nm to 455 nm) and blue-turquoise light (about 450-500 nm). 

Blue-violet light is higher energy and in the potentially harmful range, and blue-turquoise light is what impacts sleep/wake cycles. 

So, whether blue light blocking glasses work depends on what you expect them to accomplish. 

Here’s a more in-depth look at some of the claims surrounding blue light filtering glasses.

Digital eye strain

Reports of eyes that are dry, red, irritated and fatigued while using screens are so prevalent, there’s a term for it: digital eye strain. It’s a multilayered problem. When using screens, we tend to blink less, causing dry eyes and eye strain. 

Fortunately, some studies have shown improved visual comfort when using blue light filtering glasses.

How blue light impacts your sleep

Blue-turquoise light can have an effect on your circadian rhythm, or your sleep-wake cycle. An LED screen typically emits both blue-violet and blue-turquoise light, although the amount and type of blue light varies by device, manufacturer and settings. Still, the amount of blue light emitted is very small compared to sunlight. 

Blue-light glasses that are clear typically filter only blue-violet light, not blue-turquoise light, so these glasses will not have an effect on the sleep-wake cycle. A darker orange or amber tint is required to filter some blue-turquoise light. This is why it is important to remember that not all products that claim to filter blue light will filter blue-violet light or blue-turquoise light. 

Even though experts recommend putting down your phone two to three hours before bedtime, many Americans don’t. According to the National Institute of Health, 90% of Americans spend at least a few nights per week on electronics within an hour of bedtime. 

The effect of blue light on your eyes

Some blue light studies have shown an effect on retinal cells, but because they were conducted on animals or cells in a petri dish, these studies did not mimic the natural conditions of blue light exposure to a live human eye. They also did not use blue light from digital screens, according to the American Association of Ophthalmologists.

Any impact on a human retina by high-energy light like blue light is thought to be cumulative. Prolonged exposure to ultraviolet light is known to cause harm to skin and eyes — but we don’t yet know how similarly prolonged exposure to blue light may affect us.

What is blue light, anyway?

Blue light isn’t confined just to screens — it’s all around us. The main source of blue light is sunlight, both indoors and outdoors. Blue light is also found in much smaller amounts in traditional fluorescent lights, compact fluorescent light bulbs and LED lights. 

And, not all blue light is bad. The sun’s blue light in the blue-turquoise range gives us energy, helps us stay alert during the day, aids in memory and cognitive function and elevates mood. 

On the spectrum of visible light, each color of light has a particular wavelength — it’s what makes red look red and blue look blue. The wavelengths range from 380 nanometers (nm) on the blue end of the spectrum to about 700 nm on the red end. The smaller the number, the shorter the wavelength, Shorter wavelengths have higher energy and therefore more potential for damage.

Blue light itself ranges from 380 to 500 nm. Sometimes, blue light is further broken down into blue-violet light (380 to 450 nm) and blue-turquoise light (roughly 450 to 500 nm). Researchers from the National Institute of Health claim that blue-violet light can impact the eyes most at around 440 nm.