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The dangers of blue light

Reading time: 13 minutes

Celeste McGovern investigates damage from digital blue light and how to protect your eyesight and more

Compared to just a decade ago, human beings are awash, day and night, in digital light—from phones and tablets to laptops and big screen TVs, to say nothing of the proliferation of LED lights in homes and office buildings, from cars and signs, and on highways and streets.

Artificial light has not only become ubiquitous but often feels inescapable. Children are bathed in digital light at school, where they are educated on screens, and office work is done on a laptop at home into the wee hours. Even entertainment is digitized—everything from playing a video game to following a recipe on TikTok to watching a movie on Netflix means staring at a screen.

There is discussion of how this new lifestyle is affecting our society, and especially our children, who are increasingly isolated, sedentary and addicted to their electronic devices. Some dark-sky groups are advocating for turning unnecessary city lights down or off because of mounting research, often using satellite imagery to quantify outdoor lighting. Their findings show that light pollution is contributing to a host of health issues, from soaring obesity1 and metabolic disorders2 to cancer3 and overall mortality.4

Unnatural illumination is also harming wildlife. Baby turtles, for example, are straggling from beaches into Florida parking lots, misled by the lights, and some species of birds have damaged night vision that leaves them open to predators. Artificial light affects migration, hormones, reproduction and ecosystems.5

Few consider, as they scroll and message, the toll that the light from digital devices might be taking on their health. The short wavelengths in the ultraviolet spectrum (400–490 nm)—what we call “blue lights”—are especially problematic, it turns out, and the evidence that they are damaging our eyes and our bodies as a whole is growing and worrisome.

Wrinkles and acne

“Recently, due to inevitable consequences of modern life, humans are not exposed to adequate levels of natural light during the day, but they are overexposed to relatively high levels of artificial light at night,” researchers in Iran wrote a half-decade ago while reviewing the effects of blue light on skin.

“Recent studies show that exposure of human skin cells to light emitted from electronic devices, even for exposures as short as one hour, may cause reactive oxygen species (ROS) generation, apoptosis and necrosis,” they said—or, in lay language, aging and cell death. All those lights are giving us wrinkles. The effects of longer periods or frequent exposures are unknown.

Somewhat ironically, “There are reports indicating that frequent exposure to visible light spectrum of the selfie flashes may cause skin damage and accelerated skin ageing,” according to the Iranian scientists, who recommended changing the spectral outlet of smartphones’ flashes to safer wavelengths, but their concerns seem lost in the digitized world.6

The same researchers found that exposure to blue light from devices increased the proliferation of the microbe Staphylococcus aureus and its association with acne on subjects’ faces compared to those exposed to incandescent light of the same intensity and duration.7

Eye damage

The damage from blue light goes further than skin-deep, however. “Over the past decade, a growing number of studies have focused on the effects of blue light on the retina, and more recently, on the human body as a whole.”

Within a decade of LED lights’ debut in the early 2000s, ophthalmologists were noting incidents of blue light eye injury. For example, a 15-year-old male Japanese student stared at a toy containing an LED of 410 nm wavelength for 20 seconds at a time on each of two days (close to the exposure used for experimental injury of a rat retina, the researchers noted).

He noticed decreased vision and a central blind spot about two weeks later, which did not go away. “Children, especially, should not be allowed to play with such toys without being carefully instructed about their proper use and fully supervised,” the case report concluded.8

Blue light has always existed in nature, but now the human retina is bombarded with it in ways never seen in history. Because it is at the high-energy end of the visible spectrum, it may harm the photosensitive human retinal ganglion cells, the neurons that transmit information from the eye to the brain.

Prolonged exposure to blue light increases the generation of reactive oxygen species (ROS) and oxidative stress, the underlying problem in diseases from asthma, atherosclerosis and aging to cancer, diabetes, infertility and neurodegeneration. Oxidative stress is also now recognized as the driver in eye diseases including cataracts, dry-eye disorder, diabetic retinopathy, glaucoma and age-related macular degeneration. These are leading causes of blindness, and there is currently no satisfactory treatment for any of them.9

A 2023 study found that, in mice, blue light exposure (even at “safe” wavelengths) degraded epithelial cells in the retina and collapsed the inner blood-retinal barrier.10

Apart from triggering oxidative free radicals and degrading retinal cells, blue light messes with circadian rhythms and wreaks havoc on the production of melatonin and other hormones, disturbing sleep, which is critical to health.

Dark deficiency disease

Melatonin, sometimes called the hormone of darkness, is triggered by the onset of darkness and brings on sleepiness. It’s also a powerful free radical scavenger, an immune active agent and a mitochondrial regulator, offering protection against cancer, Alzheimer’s disease, multiple sclerosis, infertility and Covid-19, among other diseases.

Normally, as the sun sets, melatonin levels rise, eliciting drowsiness. Artificial light—especially high-spectrum blue light—interferes with and suppresses melatonin production up to five times more than sunlight.

Just after a two-hour exposure, blue light suppresses melatonin. That and intermittent light exposure, like turning on a phone in the middle of the night, disrupt circadian responses. Even exposure to low levels of light (5–10 lux, less than the light of a single candle) induces a circadian response.11

One study monitored students in their beds at home and gave them either a book (about 27 lux) or an iPad (about 58 lux) to read for 30 minutes before sleep. EEG monitoring showed the iPad group’s sleep quality was acutely affected.12

This “darkness deficiency” of melatonin and its tandem sleep disturbance are tied to a host of diseases, from Alzheimer’s to neurological diseases, and to poor cognitive performance. While mainstream medicine has been silent on the topic, scientists in the field are issuing red-alert warnings with study headlines such as “Women with Hereditary Breast Cancer Predispositions Should Avoid Using Their Smartphones, Tablets, and Laptops at Night.”13

The American Academy of Ophthalmology (AAO) downplays the effects of computer use, saying, “Most are only temporary and will lessen after you stop using the computer.”

However, its guidelines for children acknowledge that “Computer use and other near work activities may be driving a worldwide epidemic of nearsightedness in children, although this is not yet proven.”14

Escaping the blues

What can be done, then? Life without screens would be difficult for most people, especially when their work depends on it. Life without artificial light is virtually impossible. Where to start to save your eyes from blue light health hazards?

The AAO offers these tips to minimize blue light eye fatigue:

  • Sit about 25 inches (arm’s length) from the computer screen. Position the screen so you are gazing slightly downward.
  • Take regular breaks using the “20-20-20” rule: every 20 minutes, shift your eyes to look at an object at least 20 feet away for at least 20 seconds.
  • When your eyes feel dry, use artificial tears to refresh them.
  • Adjust your room lighting and increase the contrast on your screen to reduce eyestrain. Use a matte screen filter if needed.
  • If you wear contact lenses, give your eyes a break by wearing your glasses.

Guidelines for children

  • Make sure they view laptops and tablets at arm’s length, about 18 to 24 inches away. They should have a monitor positioned at eye level, directly in front of the body.
  • To reduce glare, position the light source behind the back, not behind the computer screen.
  • Adjust screen brightness and contrast so that it feels comfortable for them.
  • Don’t use a device outside or in brightly lit areas; the glare on the screen can cause eyestrain.
  • Avoid using a device in a dark room. As the pupil expands to accommodate the darkness, the brightness of the screen can aggravate after-images and cause discomfort.
  • Put down the device 30 to 60 minutes before bedtime. Blue light may disrupt sleep.

Step outside

Several studies show that exposure to daylight (early in the day is better) by spending time outdoors in the morning can offset the physiological effects of extended blue light in the evening. For young children and adolescents especially, exposure to natural daylight is protective against nearsightedness.

A 2013 review study published in the journal Ophthalmology looked at the relationship between time spent outdoors and myopia in nearly 10,000 children and teens and found a significant protective association with time spent outdoors.15

Use blue light–blocking glasses and screen filters

Despite their dismissal by mainstream ophthalmology (like the AAO), a 2021 review of the literature reported “substantial evidence” that blue-light-blocking glasses, or amber-tinted glasses that filter blue light, can offset the melatonin-suppressing effects of blue light.16

Various scientific studies have reported that wearing blue-light blockers for 60 minutes of light exposure led to slightly higher melatonin levels compared to baseline, while melatonin levels decreased by 46 percent without the glasses, and that insomnia sufferers had better sleep quality after just a week of wearing blue blockers for two hours before bed.17

There is some evidence that physical blue screen filters, which cover a device’s screen to prevent blue light from reaching your eyes at night, may offer the same benefits.18 Filters that are downloadable or available in device settings, such as f.lux, Twilight and Night Shift, dim blue light automatically at night and may help, though more research is needed.

Regulate indoor light

Consider the colors and brightness of your home’s lighting and make adjustments based on the time of day. You can also open and close window coverings to control exposure to light from outside. Some scientists have recommended light protocols to promote health.19

Take antioxidants

Since oxidation leads to the onset of eye and systemic damage from blue light, Italian researchers wrote in their recent review of the literature, “the role of antioxidants has become of massive interest for doctors and patients in the treatment and prevention of diseases.” Excessive light exposure accelerates photoreceptor degeneration, so anti-inflammatory agents are candidates to prevent the progress of photoreceptor degeneration as well.20

Here are some of the most studied natural antioxidant and anti-inflammatory compounds with research showing they can protect eyes from oxidation damage by light.

Melatonin. As mentioned earlier, melatonin is the hormone that leads to sleep. As low vitamin D is a “sunshine deficiency,” low melatonin results from “darkness deficiency” and has equally wide physiological effects on the body, according to a group of US and Australian researchers in a 2022 review.18 Supplementing it can improve a wide range of conditions, including sleep disorders, and offset blue light exposure.

The average human adult produces 0.1–0.9 mg of melatonin daily. “Larger doses do not always confer greater health benefits,” the melatonin reviewers say. While supplements range from 0.3 to 200 mg, too much melatonin and extended-release formats have been known to produce side effects such as amnesia or a “melatonin hangover,” trouble falling asleep, or waking three to four hours into sleep.

As well, people with certain genotypes, such as polymorphisms in the melatonin receptor 1B (MTNR1B) gene, may need hemoglobin A1C blood tests if they supplement melatonin. There are also theoretical concerns that supplementing melatonin could drive down the body’s own melatonin production and create dependence. Some people have reported vivid dreams or nightmares while taking it orally. There are reports of too much melatonin inducing cold.

Dosage: The researchers recommend starting at a “physiological” dose of 0.3 mg and increasing if necessary, except in specific conditions requiring higher doses, such as jet lag, shift work or cancer

Vitamin A. Vitamin A is a fat-soluble life-essential group of compounds famous for its roles in cell production, fetal growth, eye development, immune and nervous system function, and night vision.21 Unlike water-soluble vitamins, vitamin A might accumulate in the body, especially in the liver and fat tissue.

Active vitamin A generates a chain of reactions in the retina, allowing the transmission of optical perceptions to the brain via the optic nerve. It maintains reduction-oxidation balance. In fact, retinol binds to different proteins, acting as a redox reagent.

Dosage: The recommended daily allowance for women (not pregnant) is 1,600–1,800 mcg, for men is 2,000–2,400 mcg, and for pregnant women is 750–770 mcg

Lutein and zeaxanthin. Lutein and zeaxanthin are carotenoids found in the eyes, brain and skin. Yellow in color, these pigments play essential roles in filtering light, particularly from the blue end of the spectrum.

“As the peak wavelength of lutein’s absorption is around 460 nm, which lies within the range of blue light, lutein can effectively reduce light-induced damage by absorbing 40% to 90% of incident blue light depending on its concentration,” according to researchers at Harvard Medical School and the University of Hong Kong. “Hence the photoreceptors are protected against photo-oxidative damages from blue light.”22

That sunscreen protects the eye lens from phototoxic oxidation that cascades into eye diseases such as age-related macular degeneration, cataracts, myopathy and diabetic retinopathy.23 Lutein is also able to turn off the inflammatory cascades that lead to eye (and brain, skin and liver) disorders.24 Deficiency of these carotenoids is actually used to predict the risk of developing eye diseases, and a wealth of research suggests supplementing them for eye health.25

Dark green, leafy vegetables such as kale and spinach (which both deliver more than 10 mg per 100 g in cooked form), egg yolks, orange peppers, squash, basil and parsley are all good food sources of lutein and zeaxanthin.

Eggs are especially good as they also provide the fat for absorption, but an oil-based salad dressing helps do the job with vegetables as well. One study showed that eating a salad with a fat-free dressing barely increases plasma carotenoid content, but eating it with 6 or 28 g of canola oil (olive oil may be an even better choice) dose-dependently increases carotenoid content of the plasma.26

Dosage: The Council for Responsible Nutrition (CRN) says lutein is safe up to 20 mg/day, and most clinical studies use 2–6 mg/day; 2 mg of zeaxanthin is shown to be safe in studies

Vitamin C. Vitamin C (ascorbic acid) is a top free radical quencher, present in very high concentrations in the eye in the aqueous humor (a saline fluid) and vitreous humor (the gelatinous connective tissue in the eyeball cavity) where it acts as a sort of “physiological sunscreen” absorbing ultraviolet light, which prevents UV rays from penetrating and launching their cascade of oxidative damage.27

Not surprisingly, then, studies have linked low levels of vitamin C to the risk of cataracts.28 One study from Kings College of London followed more than 1,000 sets of British twins for a decade and determined that consumption of a minimum 300 mg vitamin C daily protected against baseline cataracts and cut its progression by a third.29

The Age-Related Eye Disease Study (AREDS Part 2) found that 500 mg/day of vitamin C helped to lower the risk of age-related macular degeneration progressing to the late stage.30

Dosage: 300–500 mg/day is sufficient for eye health, although vitamin C is safe in doses up to 10,000 mg/day

Coenzyme Q10. Coenzyme Q10 (CoQ10), also known as ubiquinone, is a fat-soluble antioxidant that helps generate energy in our cells. Because CoQ10 is ubiquitously found throughout the body (hence the name ubiquinone), it has a role in age-related diseases from Alzheimer’s to glaucoma and macular degeneration.

“Since the retina is the most metabolically active tissue of the body, with the highest consumption of energy, patients with coQ10 deficiency may develop retinopathies, suggesting that coQ10 can play an important role in pathogenesis of retinal conditions,” Italian researchers wrote in their 2022 review of antioxidants in eye health.20

Experimental research has shown that CoQ10 can reverse loss of mitochondrial function, which suggests a role for it in eye health.31 The normal concentration range of CoQ10 in human plasma is 0.8–1.2 mg/L,20 but blood serum levels of CoQ10 drop as much as 40 percent as we age.32

Dosage: In cases of deficiency, supplementation typically given to adults is 1.2–3 g/day

Astaxanthin. Astaxanthin is a naturally occurring red pigment in numerous living microbes that tiny zooplankton and krill feed on, giving the pink color to sea creatures up the food chain such as shrimp, lobster, crayfish and salmon.

A super-antioxidant whose potency is 6,000 times that of vitamin C, 550 times that of vitamin E and 40 times that of beta-carotene, astaxanthin has been shown to protect the skin, cardiovascular and nervous system with anti-inflammatory, anti-cancer and other health-boosting properties.20

In the past two decades, astaxanthin has also been shown to protect against eye diseases with underlying oxidative stress mechanisms, including macular degeneration, cataracts, diabetic retinopathy and glaucoma.33 Japanese researchers have shown that 100 mg/kg of astaxanthin inhibits light-induced retinal damage in mice.34

Dosage: Clinical studies use doses of 4–40 mg/day with no adverse events reported

Trehalose. Trehalose is a compound usually found in different species of plants, fungi, algae, bacteria, yeasts, insects and other lower invertebrates, but not in mammals. It is used by industry as a sweetener, food stabilizer and drug excipient. Because it can penetrate cells, it has also been used for its therapeutic effects on heart and metabolic disorders and traumatic brain injury. Czech researchers have demonstrated that trehalose accelerates healing of the cornea damaged by UVB radiation.35

While there is some concern about the unknown impact of trehalose, which is about half as sweet as sugar and in thousands of products, on the gut microbiome, research points to its specific antioxidant, anti-inflammatory and hydrating effects in eye disease. Trehalose eye drops (e.g., Thealoz) have been used clinically for dry-eye disease.

Dosage: Follow eye drop instructions

Curcumin. Curcumin is a pigment extracted from turmeric, a powerful antioxidant and anti-inflammatory. A growing number of recent studies have confirmed curcumin aids the treatment and prevention of cancer and inflammatory diseases, including diseases of the eye that begin with excessive oxidation.

Research has shown curcumin protects human retinal cells from cell death.36 It’s also been shown to protect against the inflammatory drivers such as those that cause dry-eye disease and uveitis, and to suppress allergic conjunctivitis in mice.37

In one study, people who took 375 mg capsules of oral curcumin three times daily for 12 weeks reported improvement in chronic anterior uveitis.38 A 2010 follow-up confirmed that a complex of 600 mg Meriva curcumin plus phosphatidylcholine, taken twice daily, helped 80 percent of patients with relapsing chronic uveitis.39

Dosage: 1,200 mg of Meriva-derived curcumin extract

Quercetin. Quercetin is a flavanol found in black tea, red wine, green leafy vegetables, fruits and onions. Recent research has confirmed its potent antioxidant, anti-inflammatory, anti-cancer, anti-aging and anti-autoimmune effects. Some researchers are considering quercetin as a safer alternative treatment to corneal transplant when oxidative damage and prolonged inflammation have damaged tissue.40

Dosage: Studies have shown that quercetin protects human eye tissue at an average daily dose of 16–23 mg/day

Fish oil. Research suggests antioxidant and anti-inflammatory polyunsaturated omega-3 oils, found especially in fish, fish oils and algae supplements, can mitigate the oxidative damage underlying dry-eye disease, glaucoma, age-related macular degeneration and more.41

Dosage: Many studies use a dose of 180 mg eicosapentaenoic acid (EPA) and 120 mg docosahexaenoic acid (DHA) twice a day; Arctic krill oil provides omega-3 fatty acids and astaxanthin, and 1,000–2,000 mg is recommended daily

Grape seed extract. Grape seed extract is a super free radical quencher42 that has shown protective effects in diseases including diabetes, obesity and autoimmune arthritis.43 Researchers have looked at grape seed in eye disease, too, showing that it reduces free radicals in eye tissue44 and protects lens cells from oxidative stress.45 Grape seed extract also protects retinal cells from oxidative stress damage—the kind that blue light induces.46

Dosage: 100–300 mg daily

N-acetyl cysteine (NAC). NAC is a precursor to the super-antioxidant glutathione, which keeps free radicals in check. Its role in bolstering the immune system (fighting Covid, for example), and combating heart disease is well documented. NAC has also recently been shown experimentally to prevent retinal nerve cell degeneration in mice.47

Dosage: 600–2,000 mg daily

Probiotics for eyes. Japanese researchers recently showed that the lactic acid bacterium Lactobacillus paracasei KW3110 can suppress inflammation in mice and prevent blue light-induced human retinal cell death. In a follow-up clinical study, subjects eating the probiotic had less eye fatigue from video blue light after four weeks compared to controls, meaning the probiotic might help mitigate blue-light-damage disorders in humans.48




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