The Dark Side of Blue Light

All About Science

Light is much more complex than you might think. When you step outside during daylight, flip on a wall switch, or stare at a computer screen or TV, the light you see is actually composed of a wide range of different kinds of light, all of which can affect your eyes, skin, and overall health.

About one third of all the visible light we see is blue light. And while exposure to blue light (and sunlight in general) is actually essential for health, too much blue light can be harmful. Here’s what you need to know about blue light, how it affects your vision, and how three simple nutrients can help protect your eyes.

What is Blue Light?

What we call “light” is in fact a full spectrum of red, orange, yellow, green, and blue light rays. Light rays on the red end of the visible light spectrum have the longest wavelengths and contain the least energy, whereas light rays on the blue end of the spectrum have the shortest wavelengths and contain the most energy.

Ultraviolet light rays have even higher energy than visible blue or violet light, and that’s why these rays are capable of producing changes in our skin that can cause both sunburn and vitamin D production.

Sunlight is a primary source of blue light, but there are also other significant sources of blue light, including fluorescent and LED lights; flat-screen televisions; and the display screens of computers, e-Readers, smartphones, and other digital devices.

Due to the high energy and short wavelengths of blue light rays, they scatter more easily than other colors of sunlight when they collide with molecules in the atmosphere. This scattering of blue light rays is what makes the sky look blue on a clear day.

Blue Light and Your Eyes

The same reason that blue light scatters more easily in the atmosphere—its high energy and short wavelengths—is also what makes it hard on your eyes. Blue light’s energetic wavelengths make it difficult for your eyes to focus. In the short term, this “visual noise” can contribute to digital eye strain and fatigue.

In the long term, blue light carries other potential risks for your eyes. The outer parts of your eyes (specifically, the cornea and lens) are good at blocking UV rays from reaching the retina at the back of your eyes, even without sunglasses. But when it comes to blue light, your cornea and lens are simply not very effective at blocking it, and it penetrates much deeper into your eyes. Nearly all of the blue light you see passes through your cornea and lens to reach your retina. This is important because studies have shown that blue light exposure can damage the light-sensitive cells of your retina.

Nowadays, the potential risks of blue light have been getting more attention because of the proliferation of digital devices. The ever-increasing amount of time most of us spend using these devices, and the proximity of these screens to our eyes, have raised concerns about the possible long-term effects of this additional exposure on eye health.

On the plus side, blue light is known to boost alertness, cognitive function, and mood. In fact, blue light is used in light therapy to treat Seasonal Affective Disorder (SAD). It also plays important roles in regulating circadian rhythm, our natural sleep-and-wakefulness cycle.

Researchers have yet to determine how much blue light is too much for optimal eye health. But if you want to be cautious, there are several ways you can protect your eyesight from overexposure to blue light. Perhaps the most proactive thing you can do to maintain your eyesight is to make sure you’re getting plenty of these well-established nutrients for eye health: lutein, zeaxanthin, and omega-3s EPA and DHA.

Nutrients for Eye Health

The most important nutrients for protecting your retina, in particular, are the carotenoids lutein and zeaxanthin.* They are the only carotenoids found in the eye, specifically in the area of the retina called the macula, which is the area susceptible to the greatest amount of light-induced damage. Together, lutein and zeaxanthin form a protective layer in the macula, and increased consumption of these nutrients is associated with increased thickness and density of that protective layer.*

Lutein and zeaxanthin benefit your eyes and vision in two ways: As filters that absorb blue light and thus prevent it from reaching your retina; and as antioxidants specific to the eye, scavenging free radicals and protecting your eyes and vision from oxidative damage.* Dark leafy greens like kale and spinach are excellent dietary sources of lutein. However, the typical diet provides only 1-2 mg lutein, while the American Optometric Association recommends we get 10 mg of lutein and 2 mg of zeaxanthin daily for optimal health.*

Omega-3s are essential fatty acids naturally found in high concentrations in your eyes, where they provide crucial support for healthy eyes and vision.* The human retina, in particular, contains more omega-3s (and especially more omega-3 DHA) relative to other tissues and organs; in fact, DHA has been reported to contribute 50-70% of the fatty acids present in the segments of the retina that contain your eyes’ photoreceptors. Adequate intake of omega-3s ensures that your retina and eyes have the essential fatty acids they need for optimal health and function.*

Together, omega-3s, lutein, and zeaxanthin are essential nutrients to help benefit our eyes and vision.* But since our bodies don’t make them, they must be consumed through diet or supplementation.

In addition to protecting your eyes from the inside with essential nutrients, you can also use physical filters that attach to your computer screen to limit the amount of blue light emitted. Of course, cutting down your screen time is another way to limit your exposure to blue light. Giving your eyes a break now and then can be a proactive step towards lifelong eye health.

* These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

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