Everything You Need to Know About Blue Light

By Kate B.
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Photo Courtesy: Marvel Studios/The Walt Disney Studios/IMDb

For beach-goers, experts always recommend a healthy coating of sunscreen to protect the skin from those pesky ultraviolet (UV) rays. But sunlight contains more than just UV light. In fact, it’s made up of red, green, yellow, blue and orange light rays, which combine to create "white light" (a.k.a. sunlight). If you haven’t sat through a high school chemistry class in a while, no worries. We’ll break down the important stuff — without getting too scientific.

As the name suggests, visible light can be seen by the human eye, and each ray reflects a particular color. The color of a given ray depends on said ray’s wavelength (see the graphic below) — or the distance between successive crests of a wave. (Side note: This means that objects get their colors through the wavelength of the light that is reflected from them. Trust us — don’t think too hard about it. Things get trippy.)

Another important relationship to note is that of wavelengths and energy: The longer the distance between waves, the less energy a ray has to offer. Think of it this way — if the wave crests are farther apart, they’re a bit lackadaisical, but if the crests come in rapid succession, there’s a frenzy of energy there. All of this means rays on the red end of the visible light spectrum have longer wavelengths and less energy, whereas rays on the blue end have shorter wavelengths and more energy.

UV rays, which aren’t on the visible light spectrum, surpass blue light in terms of how much energy they contain. That incredible amount of energy is how those rays are able to create a physical change, like tanning (or burning) one’s skin. In moderation ultraviolet radiation can be good for us (think vitamin D!), but, on the other hand, it can also produce some devastating effects (think sunburn and snow blindness!).

How Does Blue Light Impact One’s Health?

But what about blue light — these visible rays that are a few notches below harmful UV rays? Well, approximately one-third of all visible light is considered high-energy visible (HEV) blue light. Blue light is literally why the sky appears blue: These rays scatter more easily than other visible rays of light when they strike the atmosphere’s air and water molecules — and all that scattering makes the sky that vibrant blue.

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Photo Courtesy: Wikimedia Commons

There’s no escaping it, especially because daylight is our main source of blue light. But it’s not all bad: Experiencing blue light during the daytime helps regulate one’s circadian rhythms, makes one more alert, elevates cognitive function, promotes good recall and is even used in light therapy to treat seasonal affective disorder (SAD). However, human-made objects — including LED lights and display screens on flat-screen TVs, computers and smartphones — emit blue light too. Although these devices only emit a fraction of the blue light the sun emits, researchers and doctors have still voiced concerns about patients’ excessive screen time in recent years.

Perhaps surprisingly, the human eye is pretty great at protecting the retina from UV rays, but blue light is a different story. Virtually all of it penetrates the light-sensitive retina, causing damage that approximates macular degeneration — a condition that can lead to vision loss.

In addition to potentially harming your eyes over time, blue light can also lead to eye strain. If you’ve ever ended up with a wicked headache after staring intensely at an Excel spreadsheet for hours, you’re probably familiar with that particular discomfort. When we noted how blue light contributes to the sky looking blue, we mentioned that this is so because of how blue light scatters. Well, according to All About Vision, this same scattering of the blue light that emanates from screens makes for "unfocused visual ‘noise’ [that] reduces contrast and can contribute to digital eye strain."

If you don’t suffer from eye strain due to increased exposure to blue light, these inescapable rays may still have adverse effects on your health. Any sort of light — regardless of where it falls on the spectrum — can suppress the human body’s ability to release melatonin, the hormone that regulates sleep cycles. However, it’s thought that blue light quashes melatonin secretion even more than other hues do. Researchers at Harvard University compared the effects of blue and green light exposure and found that "blue light suppresses melatonin [secretion] for about twice as long as the green light and shifted circadian rhythms by twice as much."

It’s a Blue, Blue World

BluTech, a company that manufactures special blue light-filtering lenses, reports that "43% of adults have a job that requires prolonged use of a tablet or computer" — and that’s just while said adults are on the clock. Factor in all that time we spend online, texting and marathoning Netflix, and adults spend roughly 12 hours a day looking at screens and taking in blue light. So, how can you mitigate the harmful effects of prolonged exposure to blue light?

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Photo Courtesy: @felixgrays/Twitter

Well, these blue light-filtering lenses are becoming all the rage. Although not as ubiquitous as Away suitcases or Blue Apron commercials, you’ve probably heard commercials for blue light-filtering specs from Felix Gray or Warby Parker on your favorite podcast or radio talk show. Felix Gray glasses, for example, pride themselves on having a blue light-filtering material embedded inside, which the company says will curb eye strain, headaches and sleep disruption.

If you’re not into the glasses route, experts recommend taking screen breaks, both at work and at home; keeping screens clean to reduce glare and further eye strain; changing your abrasive white display background to something less bright; blinking more often; and avoiding screens for at least 30 minutes to an hour before bed because screens stimulate your brain. Maybe it’s time to trade that fancy blue light-emitting tablet for a Kindle Paperwhite, or, you know, a good old-fashioned book.