Campus Queries: Is blue light harmful for us?

While some companies have profited off fears of blue light, Colin McCannel, a professor of clinical ophthalmology at UCLA’s Stein Eye Institute, said many of these fears aren’t based on scientific research.

There is little credible evidence from real-life scenarios or human studies that support that blue light adversely affects eye health, McCannel said. Laboratory experiments can demonstrate that blue light is toxic, especially in high doses and to certain cells, and that this toxicity is dose-related, he said. However, the idea that blue light causes retinal disease has never been proven.

“There are a few epidemiological studies on light exposure and macular degeneration (retinal damage that hinders vision) showing there is a very small increased risk of macular degeneration among those with excessive light exposure,” McCannel said. “However, most studies do not find such an association, and no study proves a causal relationship between light/sun exposure and macular degeneration.”

McCannel said computers, cellphones and LED lights emit more blue light than traditional incandescent bulbs. However, the amount of blue light the eye is exposed to from modern electronics and LED bulbs is small compared to being outside in the sun on a normal day.

“Until there is more research that furthers our understanding of whether or how blue light affects disease development or progression, there is not much to worry about,” he said.

McCannel said the first “blue light scare” occurred in the 1980s, when new research showed that some retinal cells can be killed by blue light. An industry of blue-light-blocking sunglasses then emerged but faded due to lack of demonstrable benefit.

“For now, I do not think anyone needs to do anything special to avoid blue light retinal damage. In general, it is a good idea to wear sunglasses outside when it is very bright,” he said. “There are large amounts of epidemiological evidence that people exposed to lots of sunlight get cataracts (clouding of the lens in the eye) at an earlier age.”

However, McCannel said there is emerging evidence that blue light is important in circadian rhythm control. Exposure to large amounts of blue light in the late afternoon or evening can disrupt the circadian cycles by suppressing melatonin, affecting the length and quality of sleep.

“Reading on a tablet or cellphone, which have lots of blue light mixed with white light, can cause sleep difficulties, such as not being able to fall asleep or having less restful sleep,” McCannel said. “Therefore, it is advisable to use software that shuts down the blue component of the light when reading off these devices in the evening.”