For the most part, light is perceived as a positive thing. In fact, it’s often used to portray the “good” side vs. the “evil” in stories and art. However, it’s important to note the potential dangers that can accompany light we’re exposed to on a daily basis. The only two parts of the body that are susceptible to light damage are the skin and eyes, and the kinds of dangerous light that are most prevalent are ultraviolet (UV) and blue light.
What Is UV Light?
Ultraviolet (UV) light is part of the non-visible light spectrum, meaning we can’t see it with our eyes alone. UV light is made up of short wavelengths of light, giving it a higher amount of energy than most other types of light. The main source of UV light is the sun, and tanning beds are a manmade source to mimic sunlight’s tanning quality in record time. Though many people think that UV exposure is always the same when the sun is up, it actually varies based on season and time of day. During the summer, 10 am and 2 pm has the highest exposure, while 8-10 am and 2-4 pm has the highest exposure during winter.
There are three kinds of UV light:
- UVA is the least damaging of the types of UV light.
- UVB is the more energetic and damaging type of UV light we’re exposed to on a day-to-day basis. It can cause sunburns, skin thickening, wrinkling, and possibly destroy Vitamin A and damage DNA, leading to several skin-related health concerns.
- UVC is mostly absorbed by the atmosphere, but it can cause permanent tissue damage with brief exposure.
What Does UV Light Do?
Though UV light does little to nothing to help us physically see, it does help our bodies produce enough Vitamin D when absorbed in moderation. However, ultraviolet radiation (UVR) is undoubtedly dangerous to our eyes and the surrounding structures. It can cause oxidative photodegradation, which means things called free radicals are produced in excess and our bodies can’t fight them all, leading to cells being destroyed.
The parts of the eye most damaged by cumulative UV light (the continuous exposure over time) are the cornea and lens, or the outermost layers of our eyes. Although we shouldn’t dismiss these damages, they can generally improve with proper care.
Our eyes have evolved over thousands of years and have developed natural UV protection over time. The cornea, the smooth outer casing of our eyes, and the crystalline lens, the piece of our eye that intakes visual stimuli, absorb the majority of UV light that enters the eye. However, that doesn’t mean we can forgo any further protection. As we mentioned, UV light damage happens with repeated exposure over time. To mitigate the damage, use sunglasses and hats to keep the UV light wavelengths away from your eyes and wear long sleeves or sunscreen to protect your skin. Be conscious of the amount of time you’re spending outdoors with or without proper protection so you can limit overall exposure.
What Is Blue Light?
Although less well-known than UV light, blue light is another type of light that we have exposure to on a daily basis that can potentially cause damage to our eyes. Part of the visible light spectrum, this type of visible light is the closest to UV light on the light spectrum. It has the shortest wavelength of all visible light, and, therefore, has the highest energy of the visible light spectrum.
Like UV light, the main source of blue light is the sun, but there are many more manmade sources we encounter in our daily lives. Compact fluorescent lights (CFL) and light-emitting diode (LED) lights also emit this type of blue light. That means that any digital devices that uses LED screens (TVs, tablets, smartphones, e-readers, computers, etc.) also emit high-energy blue light.
What Does Blue Light Do?
High-energy visible (HEV) blue light penetrates the eye deeper than UV light does, but like UVR, cumulative exposure can damage our retinas, the part of the eye that houses the sensitive cells responsible for vision. Unfortunately, almost all the sources of blue light emit this harmful wavelength, increasing our chances of accumulating damage. Visual cues impacted by blue light include:
- Color vision
- Depth Perception
- Contrast sensitivity
- Time perception
Although the amount of blue light emitted by LED screens is a fraction of that emitted by the sun, we tend to spend a lot more time looking at screens at very close distances to our eyes. Another important consideration is how new these artificial sources of light are. While our eyes have had generations to adapt to UV light, digital screens are relatively new in the scheme of light sources, meaning we don’t know for sure the cumulative impact it can have.
What we do know is that there are several vision-related symptoms that are attributed to screen use and blue light. With the shorter, more energetic wavelengths, blue light scatters more easily, creating a flicker sensation that can make it difficult for our eyes to focus on and reduce visual contrast, sharpness, and clarity. This is often linked to the common complaints of eye strain, headaches, and eye fatigue felt after many hours on a screen.
Positives of Blue Light
Blue light can also be seen in a positive light (pun intended). This type of light helps control our circadian rhythm or our sleep-wake cycle. When blue light enters the eye, it triggers the production of cortisol, the “wake” hormone, and the suppression of melatonin, the “sleep” hormone. In fact, blue light is better at kicking that 2 pm feeling than a cup of coffee! However, this effect can also have negative implications. One Harvard study found that when we look at a tablet vs. a printed book before bed, it can push back the time we fall asleep by 2 hours.
Blue light can also be used to elevate mood in people with seasonal affective disorder (SAD), a type of depression that usually starts around fall and continues throughout winter to subside in spring. Additionally, blue light’s ability to scatter more easily helps make a cloudless sky look blue!
Blue Light Protection
Like UV light, reducing exposure is the main suggestion for reducing blue light’s impact on our bodies. While turning off screens completely is unrealistic, especially in today’s society, its recommended to try and reduce the time spent in front of screens and take frequent breaks to help give your eyes a break. Additionally, screen covers and filters and blue light glasses can help reduce the amount of blue light your eyes need to absorb.
Along with external protection like glasses and filters, you can increase your internal blue light protection. There’s a specific part of the center of the retina, called the macula, that can be damaged by blue light. Macular pigment is a protective layer that absorbs blue light before it reaches the macula and damages it, and this protective pigment is made up of two powerful antioxidants called zeaxanthin and lutein. Macular pigment is dense when it’s healthy, and to keep its density up, we need to support it through dietary intake of zeaxanthin and lutein.
Unfortunately, these two important antioxidants are scarce in our diet. In fact, we’d need to eat 20 ears of corn a day to get the amounts of zeaxanthin our eyes need! That’s why many eye care professionals recommend supplementation for their patients. EyePromise® is the #1 doctor-recommended eye vitamin company, and our products are designed with the amounts of zeaxanthin and lutein our eyes need to maintain a healthy macular pigment. For screen time specifically, we have EyePromise Screen Shield™ Pro for adults and Screen Shield Teen for kids.
Regardless of which light you’re exposed to most, protection and moderation are key to protecting your long-term eye health. Be sure you talk to an eye care professional about ways to protect your family and your eyes.