How Blue Light Affects Our Eyes

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. 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.

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.

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.

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.

For now, there are screens for tablets that claim 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. More research needs to be done to see whether those screens or apps actually work.