blue light on eye

The Truth About Blue Light

Many of us have never given blue light much thought. So, news about screen time being damaging poses a few questions. Just how concerned should we be about this? Is all blue light bad for us? If it is, then why does blue light exist at all? We’ll touch on all the above, talk about what you can do at home, and explain how to make changes at work to optimize your blue light experience.

The importance of light

It’s no secret that we need light. But do we need all kinds of light? Astronauts on the International Space Station experience multiple “sunsets” per day due to the Space Station circling Earth once every 90 minutes. Since most people operate on a 24-hour cycle known as a circadian rhythm, this environment can really take its toll. Studies conducted between 2001 and 2011 on both space shuttle and ISS crews, found that astronauts were sleeping considerably less than they were on Earth.

To address this problem, NASA ordered research known as the Lighting Effects Study to coincide with a new installation of lighting all over the ISS. All of the fluorescent lights on the ISS are being replaced with LEDs, which are more energy efficient and safer types of bulbs than fluorescent or incandescent.

Another reason for the switch? NASA will be using three different light settings on the ISS, one of which is a “pre-sleep” lower-intensity blue wavelength-depleted light that, in theory, will help regulate the circadian rhythms of astronauts aboard.

What is blue light?

In order to talk about blue light we should first address wavelengths and energy. The spectrum of visible light can be broken down into all the colors of the rainbow and everything in between. A portion of that visible light spectrum is comprised of blue light. Blue light is classified as wavelengths that measure 380-500 nm. These are short wavelengths, as opposed to red visible light, which are longer wavelengths. Also worth noting is that the shorter the wavelength, the more energy it has.

Approximately one-third of all visible light is classified as high energy visible (HEV) light, or blue light, meaning it produces more radiation.

Blue light exposure can come from more places than just the sun. The most common sources are fluorescent lights, CFL bulbs, LED lights, flat screen LED TVs, computers, phones, and tablet screens.

However, when compared to the sun, exposure from these sources is minimal. Still, the concern exists because of the time people spend each day looking at those blue light sources, the proximity of the sources to our eyes, and also the times of day in which people have these lights and devices in operation.

What does it do?

The two biggest concerns over blue light have to do with the physical effect is has on your eyes as well as the role it plays in regulating your circadian rhythm, as we mentioned earlier. Studies are still ongoing, but we have some early information that’s worth considering.

The eyes take quite a beating from blue light. Children are at a greater risk to such damage because their eyes absorb more blue light than adults’, possibly due to the fact that they are still developing.

Let’s break down exactly how each part of the eye is affected by blue light.


The cornea is the transparent part of the eye that covers the iris, pupil, and anterior chamber. It accounts for approximately 2/3 of the eye’s total optical power. When irradiated with blue light, the result is ocular inflammation and a decrease in corneal epithelial cells, which make up the protective tissue covering the front of the cornea.


The lens works alongside the cornea to help refract light to be focused on the retina. Cataracts are one of the leading causes of blindness worldwide. They occur when the lens becomes opaque, and sunlight is known to be a leading cause.

Studies have shown that blue light can induce the production of reactive oxygen species in the mitochondria of lens cells, leading to the development of cataracts.


The retina is a thin layer of tissue that lines the back of the eye on the inside. It receives light that the lens has focused, converts that light into neural signals, and then sends those signals to the brain for processing.

Blue light is dangerous because the light can penetrate through the lens to the retina and cause what is known as retinal photochemical blindness. This is why looking directly at the sun is so damaging to our eyes.

Blue light exposure may increase the risk of macular degeneration. The fact that blue light penetrates all the way to the retina (the inner lining of the back of the eye) is important, because laboratory studies have shown that too much exposure to blue light can damage light-sensitive cells in the retina.

Effects on sleep

That covers all the ways that blue light can directly affect you. What about indirectly? For that, we’ll shift gears and talk about its effect on our sleep cycle.

While these effects may be subtle, they are far-reaching. When your circadian rhythm is out of whack, the result is reduced alertness, memory, and cognition. It is why car accidents increase the day after clocks “spring ahead” for daylight savings.

Circadian rhythm, by definition, helps determine our sleep patterns based on the 24-hour day/night cycle. Your body receives information about incoming light from the optic nerves, which relay the information from the eyes to the brain. Studies performed on mice show that this disruption leads to weight gain, impulsivity, slower thinking, and other physiological disorders.

Blue light enters the picture when it comes to the body’s production of melatonin, bringing us back to the original conversation about NASA and their astronauts.

When the blue light found in daylight is present, melatonin production is halted and serotonin production increases, getting people ready to begin their day.

At night, the opposite happens. The sunlight is gone, the eyes are picking up longer wavelengths, and the melatonin production increases, making people drowsy and ready for bed. Our bodies have evolved these adaptations from living for hundreds of thousands of years on a planet with predictable day/night cycles.

However, with artificial light now playing the role of the midnight sun, our melatonin production can be disrupted, affecting not only how long we sleep, but also the quality of sleep. And it bears repeating, when you have a bad night’s sleep, you pay for it the next day.

The body’s need for sleep is not like its need for food, consumption of which can be delayed without harm. In terms of our body’s needs, sleeping is slightly more akin to breathing.

It can’t all be bad, can it?

As we pointed out above, blue light is necessary, but so is limiting your exposure. Research shows that this high energy light boosts alertness, helps memory and cognitive function, and even elevates mood.

Light therapy for seasonal affective disorder (SAD), a type of depression that is related to a change in seasons, utilizes a significant amount of HEV blue light waves to help improve mood. Exposure to blue light during daytime hours helps maintain your natural circadian rhythm.

While there are dangers related to overexposure, blue light is by no means a bad thing. Just like sunlight—think about getting a little sunlight without getting a sunburn.

What can I do to protect myself? What can I do at my workplace?

This is a safety concern that affects anyone with a television, computer, or smartphone—which is to say everyone. There are plenty of steps you can take if you haven’t already done so to limit the effects that blue light has on your eyes.

Consider getting a blue light filter for your devices. Most computers have them built in, and smartphones come with a timer that will turn them on automatically once it becomes late enough. If your model is unequipped, you can download an application that will work in its place.

Another way to handle blue light is to buy eyeglasses specific with blue light cancelling filters. Photochromic lenses, made popular by the brand Transitions, will also do the trick (but you might not look as cool). Even if you don’t wear prescription glasses, you can get plain and reading glasses with blue light filters. Also, limiting screen time will help.


This is an important thing to consider from a workplace safety standpoint. If you or your teammates are exposed to too much blue light, either from a late day in the office, or playing video games too late at night, your behavior and performance will be affected the following day, and possibly even the days after that.

If you are serious about this for your staff or teammates, consider utilizing Safety Grant funds on glasses or filters for your workplace. An improvement in sleep means an improvement in alertness and a reduction in accidents.