With modern luxuries, most people can organize a spreadsheet, read a book, watch a movie, and video chat with someone in another hemisphere—all from the same device. However, when you conduct these activities digitally, you aren’t actually staring at a book or a family member thousands of miles away, you’re staring at a screen. And that screen is emitting blue light into your eyes. Exposure to blue light at both the home and the workplace can be a problem for your circadian rhythm and health.
How Does Light Affect Our Sleep Schedules?
For most of history, light has served the essential purpose of visibility. However, more recently, the impact of light on our sleep schedule has become a concern.
Light has a profound impact on human circadian rhythms. Most living things have circadian rhythms, which comprise the physical, mental, and behavioral changes experienced over a 24-hour cycle. Our body’s clock gives us an innate sense of time, helping to guide our bodies and minds through the circadian cycle. Naturally, light shifts the phase or even resets the clock.
Light helps suppress melatonin: a hormone produced by the brain that times your circadian rhythms. The production of melatonin is in response to darkness. At night, your body naturally increases melatonin production, making you feel tired and ultimately aiding in sleep.
What Is Blue Light?
What is particularly impacting the circadian clocks of people in the 21st Century is blue light.
Between ultraviolet (UV) and infrared radiation (IR) is the visible spectrum of light, the wavelengths of which range from 360 to 720 nm. Visible light is broken up into short- (blue) medium- (green) and long-wavelength (red) radiation.
Blue light begins at 380 nm and ends at 500 nm. The sun remains the largest source of blue light. Artificial sources, which are relatively new inventions in human history, include fluorescent lights and LED (light-emitting diode) lamps, as well as TVs, monitors, smartphones, and tablets with LED or LED-backlit screens. Basically, whatever you’re reading this on is emitting blue light.
One study found that on a typical summer day, blue light accounted for 25% of the sun’s rays, approximately 30% of radiation emitted by electronic devices, and approximately 6% to 40% of that emitted by indoor lights.
Is Artificial Light Anything New?
Manipulating light for illumination in the evening and night is nothing new, as people have been using torchlight and candlelight for millennia, and, of course, Thomas Edison invented the incandescent lightbulb in 1879. Being awake at night is also not unusual. In fact, in the Middle Ages, while people would go to sleep not too late after dusk, they would practice a pattern of “two sleeps,” by which they would wake up around midnight, conduct some activities, and then return to sleep until the morning.
How Artificial Blue Light Is Becoming More Common
Artificial light has been around for a while, but a dependency on devices after sundown, paired with exposure to these devices and better artificial illumination during the day, has brought to light the effect that short-wavelength blue light has on the human body. In 2023, the average person in North America owned around 13 devices, a number up 63% from just 5 years prior. Around the world, each person spends 6 hours and 40 minutes on average per day on screens.
Many computer and device screens are LED or LED-backlit, making screens a major source of artificial blue light. The increased use of LED lightbulbs for room lighting has also been a factor. Light-emitting diode (LED) technology has grown significantly in recent years, with LED being today’s most rapidly developing lighting technology. By 2035, the US Department of Energy projects the majority of lighting installations to use LED technology.
LED favorability derives from the clear advantages of the lighting technology. LEDs can emit lights in a range of colors and in a specific direction, and they emit very little heat. Compare that to incandescent bulbs and compact fluorescent lamps (CFLs), which release 90% and 80% of their energy as heat, respectively. A good quality LED bulb can last 3 to 5 times longer than a CFL and a whopping 30 times longer than an incandescent bulb.
Residential LEDs, especially ENERGY STAR products, use at least 75% less energy and last up to 25 times longer than incandescent lighting.
While LEDs are rapidly growing in use due to these advantages over other types of lighting, they do emit more blue light than incandescent bulbs.
What Are the Negative Aspects of Blue Light?
Artificial blue light is all around us, and we are constantly under its exposure, but how exactly does it impact human health? As an essential part of our circadian rhythms, blue light inhibits the production of melatonin. So, the later you are exposed to blue light in the night, the harder it is going to be for you to fall asleep. Lack of sleep, resulting from light exposure or any source, is linked with numerous health problems, including heart disease, kidney disease, high blood pressure, diabetes, stroke, obesity, and depression. Sleep deficiency is also known to cause human mistakes and injury. While driving, sleepiness is responsible for serious injuries and even death. In the workplace, sleep deprivation can be a serious hazard.
Beyond its negative effects on the sleep cycle, research in recent years has lent insight on other potential health problems deriving from blue light exposure. While blue light does not cause acute harm to the retina, there is still debate as to whether chronic exposure may have a cumulative impact on the eye. One study also looked into the potential for artificial blue light in causing skin pigmentation disorders, a concern that rose during the COVID-19 pandemic.
However, it should be noted that lack of lighting, rather than too much lighting, is often a problem in the workplace. Bad lighting has an association with negative mental and physical health effects, including eye strain, headaches, fatigue, and anxiety. Lack of workplace daylight exposure can also lead to seasonal affective disorder (SAD), a form of clinical depression resulting from lack of sun exposure in the winter, which is known to affect anywhere between 5-10% of the population. Blue light is a known treatment for SAD.
What Can Workers Do to Protect Themselves?
One of the simplest things people can do to prevent the effects of short-wavelength light on their sleep schedule is turning off electronic devices some time before going to sleep. For those who find that to be too difficult, experts recommend dimming the brightness of devices or making use of programs that filter out short-wavelength light in the evening.
In the workplace, the classic “20-20-20” rule holds true for protecting your eyes against strain. Every 20 minutes, shift your eyes to look at an object at least 20 feet away for at least 20 seconds.
Conformity Assessment for Occupational Safety and Health
Worker health is a key concern, and one that should never be taken lightly. Due to its importance, occupational safety and health is a major interest in the conformity assessment arena. Numerous standards bodies have developed standards to help protect worker health. The ANSI National Accreditation Board (ANAB) accredits bodies that issue certifications to numerous sector-specific programs that assure quality products for consumers, such as ENERGY STAR, and the competency and safety of workers, such as ISO 45001.