What is the blue light from our screens really doing to our eyes?

Girls using laptop at night

An eye doctor says he’s recently seen a few 35-year-old patients whose lenses, which are typically clear all the way up until around age 40, are so cloudy they resemble 75-year-olds’. A sleep doctor says kids as young as toddlers are suffering from chronic insomnia, which in turn affects their behavior and performance at school and daycare. A scientist finds that women who work night shifts are twice as likely to develop breast cancer than those who sleep at night.

What do all these anecdotes have in common? Nighttime exposure to the blue light emanating from our screens.

You’ve probably heard the hype these past few years: being in the presence of light at night disrupts the body’s natural circadian rhythms by suppressing the production of melatonin, a sleep hormone. But melatonin does far more than help us get sleepy – it’s also an antioxidant that appears to play a pivotal role in slowing the progression of cancer and other diseases.

“I’ve been spending a lot of the past 20 years worrying about it,” said Dr. Richard Hansler, who clocked in 42 years at GE Lighting developing “all kinds of bright, beautiful lights” before his move to John Carroll University in Ohio, where he studied the effects of light at night on our health. It was the mid 1990s, and at that point, he said, his concern wasn’t widely shared.

“I discovered that using light at night is bad for people’s health and interferes with their sleep. I felt a moral obligation to do something about it, particularly when I learned it’s the blue component in ordinary white light that is suppressing the production of melatonin. And melatonin not only helps you sleep but is a marvelous material that has a very big influence on health in general; specifically, if you don’t have enough you may develop diabetes, obesity, heart disease, and even a couple kinds of cancer.”

When the stars go blue

The impact of blue light on melatonin production was only recently confirmed, in 2001, when scientists found that light in the blue spectrum — the 415 to 445 nanometer range — disrupts melatonin. Because it is so bright, blue light is used widely in pretty much all LED devices, including phones, tablets, laptops, and TVs. And because it is so hot, it appears to be wreaking all sorts of havoc on our eyes, on melatonin, and consequently, on our health.

The latest research, in fact, overwhelmingly suggests that delayed production of melatonin due to blue light exposure at night is causing far more problems than insomnia, from diabetes and certain types of cancer to lupus and migraine headaches. Optometrists are even seeing high levels of retinal stress in young people that could lead to the early onset of macular degeneration, which in extreme cases can cause near blindness.

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“Here’s what doesn’t need research: 415 to 445nm is super hot light, and if it’s really focused and brought up close – when you’re talking about a tablet six inches from a kid’s face – it’s got to be significant,” said Dr. William Harrison, a renowned optometrist in Laguna Beach, Calif., who has been following the research on blue light closely for the past year. He said the research is compelling, but that the medical profession is slow to catch on to the concerns.

Because artificial light at night has only been around for the past century or so, and the hotter, brighter blue light has only been so heavily concentrated in our light sources for the past 10 or 20 years (the previously popular incandescent bulbs don’t emit the same amount of blue light, which is stronger in CFLs but stronger still in LEDs), its long-term effect on our eyes and bodies remains unknown.

Screening for problems

For those who like to read the scientific literature directly, here’s a quick tour of some of the latest findings, and a search on blue light and melatonin via the U.S. National Library of Medicine’s PubMed search tool can yield larger results:

  • Room light not only suppresses melatonin production, but it could also impact sleep, thermoregulation, blood pressure and glucose homeostasis
  • Blue light is considered a “carcinogenic pollution” that in mice correlates with higher cancer rates
  • A lack of melatonin is linked to higher rates of breast, ovarian, and prostate cancers, while blocking those blue rays with amber glasses is linked to lower cancer rates
  • Exposure to blue light in people appears to have an impact on mood
  • Lower melatonin in mice is linked with higher rates of depression
  • Too much light exposure can cause retinal toxicity
  • Blue light exposure may be playing a role in the higher incidence of cataracts and macular degeneration seen today

The more Hansler conducted his own investigation into the impact of blue light on various aspects of human and animal health, the more he felt he had an obligation to do something. In 2005, he and a group of physicists at John Carroll University developed light bulbs that don’t emit blue light and goggles that block out that part of the spectrum, and he has since written a handful of books on the subject. (If you’re doing the math, yes, Hansler is now 90 years old and no, he hasn’t yet retired.)

A few developers of goggles and glasses that block blue light exist now, including Lighting Science out of Florida. In fact Dr. Michael Breus, the “Sleep Doctor” who regularly appears on shows like Dr. Oz, is so convinced by the science that he’s bought Lighting Science’s Good Night Bulb (with low levels of blue light) for his bedroom and the Awake & Alert Bulb (with more blue light to energize in the mornings) for his bathroom. Astronauts even use the bulbs to help regulate their sleep cycles on the International Space Station, which orbits the Earth every 90 minutes.

It remains unclear whether our screens themselves will soon emit less blue light — Hansler is pessimistic because he says that changing the amoung of blue light will be like admitting that the screens are causing health problems, and lawsuits could ensue. For now, there are screens for tablets that purport to filter out the blue light, and as well as apps that let you put your device in a bedtime mode where the light contains less blues and more ambers. Hansler is suspicious of whether those screens and apps work, and wants more research done.

In the meantime, does this mean we all need to refrain from any TV or lighting at all in a bedroom in the hour or two prior to bedtime, in a room so dark you can’t see your hand in front of you? “I think that’s crap,” Dr. Breus says. “If I told everybody to put themselves into a pitch dark room at 8 at night at 68 degrees with no noise, would people sleep better? Maybe. But you have to have a fairly decent amount of light and in close proximity.”

Featured photo courtesy Shutterstock user kryzhov.

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