The Dangers of Blue Light
by Lisa DiFalco
Blue light exposure is not always dangerous. Blue light is found in the spectrum that makes up sunlight and is helpful in regulating circadian rhythm, boosting alertness and elevating mood. Sunlight is the largest source of blue light, and children with too little exposure to sunlight may be at increased risk for myopia. However, while it appears that a moderate amount of blue light is necessary for proper functioning, excessive blue light can be detrimental to one’s health. A growing body of research shows an association of blue light exposure to vision issues, sleep problems and serious health concerns. Learn more about blue light dangers and how to avoid excessive exposure to blue light.
Excessive Blue Light
Technology has allowed individuals to enjoy a significant amount of light at night. This can interfere with the body’s natural rhythms and signal to the body that it must stay alert even though it is time to rest. Anne-Marie Chang, Harvard University neuroscientist said:
“We have known for quite awhile now that light is the most powerful cue for shifting the phase or resetting the time of the circadian clock. We also know that melatonin is present at low levels during the day, begins being released a few hours before bedtime and peaks in the middle of the night. Past studies have shown that light suppresses melatonin, such that light in the early evening causes a circadian delay, or resets the clock to a later schedule; and light in the earlier morning causes a circadian advancement, or resets the clock to an earlier schedule.”
Blue wavelength light, out of all of the colors, seems to disturb individuals the most when used during the night. Exposure to blue wavelength light comes not only from electronics with screens, but also from energy-efficient lighting. Other than sunlight, sources of blue light include:
- Computer monitors, tablets and smartphones.
- LED light.
- Flat screen LED televisions.
- Compact fluorescent light (CFL) bulbs and fluorescent light.
Adults and children are exposed to increased amounts of blue light compared to years past. In a recent study, it was found that children’s eyes “absorb more blue light than adults” when using digital devices.
Blue Light and Vision
Blue lights can pass through the more exposed structures of the eye and reach the retina. There is some evidence that this light may prematurely age eyes and impact vision. Vision issues that may be related to excessive blue light exposure are:
- Digital eyestrain and a decrease in contrast.
- Retina damage and age-related macular degeneration.
New technologies are available to reduce exposure to blue light from devices. Reducing screen time and frequent breaks from looking at a screen are easy ways to better manage blue light from the technologies that have become part of the modern lifestyle.
Blue Light at Night
Night shift workers are a group that may be increasing their risk of obesity, heart disease, diabetes, and breast and prostate cancer. The exact mechanism is not yet known. However, it is known that light exposure suppresses melatonin secretion. Melatonin is a hormone which can influence circadian rhythms. Lower melatonin levels may explain the preliminary evidence of links to cancer.
Researchers experimented by changing the schedule of 10 people. As their schedule changed, so did their circadian rhythms. Researchers saw an increase in blood sugar levels and lower levels of the hormone, leptin. Leptin influences feelings of hunger, and higher blood sugar levels placed participants in a prediabetic state. This Harvard study showed the potential of blue light to be connected to the development of diabetes and obesity. Individuals who do not sleep enough or experience “short sleep” may be at increased risk of diabetes, cardiovascular problems and depression.
Chang and colleagues researched the impact of reading from a light-emitting device and compared it to reading from a print book. They found that participants reading from a device:
- Required more time to fall asleep.
- Experienced less REM sleep.
These participants also took longer to wake up and were sleepier after an eight-hour sleep episode. Quality of sleep and level of alertness the following day may be negatively influenced from blue-light exposure before bedtime.
Blue Light and Energy-efficient Lighting
In order to become more energy efficient and help the environment, many people have turned to using energy-efficient lighting. Fluorescent light bulbs and LED lights do provide more energy efficiency than traditional incandescent bulbs. They also give off more blue light. Incandescent lights do produce some blue light, although less than most of the fluorescent light bulbs available.
Reduce Blue-light Exposure
There are a number of suggestions to limit blue-light exposure.
- During the two to three hours right before bed, avoid viewing bright screens.
- Wear blue-blocking glasses or download an app to filter blue and green wavelength at night. This will help those that need to use electronic devices at night and individuals working night shifts.
- Red light has the least influence on the circadian rhythm. Consider using dim red lights in bedrooms.
- Add screen filters to computer screens, tablets and smart phones to reduce blue light emissions.
- Use computer glasses that have yellow-tinted lenses that increase contrast and help block blue light.
- Wear anti-reflective lenses to block blue light from digital devices and the sun.
- Consider choosing an Intraocular lens (IOL) that protects eyes from blue light. This will replace a cloudy lens during cataract surgery.
Young users may be particularly vulnerable to blue light overexposure. Children’s eyes have not developed to the state of their parents’, and they can experience more damage than adults from blue light exposure. Dr. Bridgette Shen Lee, optometrist at Vision Optique, said:
“For children, especially from birth to age three, the crystal lenses in their eyes are not fully developed. So it goes straight through, it causes a lot more damage in children’s eyes than it does in adults.”
According to the American Academy of Pediatrics, children younger than two years of age should not be exposed to digital devices, and older children should only be allowed up to two hours on a device daily.
Families, educators, shift workers and healthcare professionals would do well to learn about blue light and current recommendations to limit exposure.