By Gregg Kleiner
We live in a modern world that is awash in artificial light from fluorescent tubes, energy-efficient LEDs and computer screens. The light from these relatively new innovations might be taking a toll on our health in ways we are only beginning to understand.
Many of us have seen the ghostly, pale bluish glow cast upon a person’s face by a mobile phone or computer on a dark night. But light at the blue end of the color spectrum doesn’t always appear blue; the glow might look like a warm white or other color. And it is emitted from a wide range of sources in addition to our smartphones and laptops. They include street lights, headlights on new cars and even the holiday lights we put up during the dark months of winter.
Blue light lies near one end of the visible light spectrum. Its short wavelengths carry higher amounts of energy than the longer wavelengths of red and yellow.
An Oregon State University research team led by Jaga Giebultowicz, a professor in the Department of Integrative Biology, is tapping one of the most well-used model organisms in biology, the fruit fly (Drosophila melanogaster), to study the health impacts of artificial blue light.
Although the fruit fly is many times smaller than the canaries once used by miners to detect the presence of odorless, toxic gases inside coal mines, the new research is enlisting these small flies to serve a somewhat similar role – helping human beings to understand the potential health risks from something we cannot smell or taste but are bathed in for many hours every day.
Giebultowicz and her team’s early research results suggest that cumulative, long-term exposure to artificial blue light impacts brain function, accelerates the aging process and significantly shortens lifespan.
A Brief History of Light
Blue light occurs naturally in sunlight. It is needed for photosynthesis and gives the sky its blue hue. Before humans invented artificial light sources, however, we were exposed to the sun’s light for only a limited number of hours each day. When darkness fell, diurnal creatures like humans went to sleep, waking when the sun rose again the following day. These cycles of dark and light are important for our biological clocks, the cellular machinery that generates circadian rhythms and keeps our brain and other organs functioning correctly.
Today, artificial light has extended daytime and reduced our exposure to darkness. We turn on lights as soon as it begins to get dark, we check our smartphones in bed and then we sometimes rise when it’s still dark out. We flip switches to produce instant artificial light.
Since the invention of electricity, artificial lighting has evolved from incandescent bulbs and fluorescent tubes to light emitting diodes (LEDs) that take many forms. Incandescent light bulbs give off very little blue light compared to LEDs, which are energy efficient but emit a high fraction of light in the blue range, often peaking at a wavelength of 460 nanometers.
We don’t yet know the full impact of exposure to this new blue light on human health, but research by Giebultowicz is beginning to illuminate some of the consequences.
She draws a comparison between the fruit flies in her lab and those yellow canaries in the mines. “These fruit flies might be telling us that something could be happening that we might not be aware of,” says Giebultowicz, whose latest research paper was published in the journal Aging and Mechanisms of Disease last October.
Giebultowicz has studied biological clocks for years and collaborated with the researchers who won the 2017 Nobel Prize in Physiology and Medicine for their work on biological clocks. She notes that cells and neurons function in a similar manner in humans and in fruit flies.
“Fruit flies are an excellent model for biomedical studies,” she says. “In a way, we are just big flies, only less pretty and without wings.”
The lifespan for fruit flies is approximately 70 days, so one day in the life of a fruit fly corresponds to about one year of life for humans, assuming a human lifespan of roughly 70 years.
Light Versus Dark
In one experiment, the research team maintained a group of fruit flies in 24-hour, total darkness. They maintained another group in alternating cycles of 12 hours of dark followed by 12 hours of exposure to artificial blue light from LEDs.
Because light-dark transitions are key to synchronizing circadian rhythms in different cells, Giebultowicz expected that the flies reared in total darkness would live shorter lives. However, she got a surprise. The flies kept in the light-dark cycles showed symptoms of accelerated aging, brain neurodegeneration and reduced lifespan when compared with the flies reared in constant darkness.
Subsequent research showed that the lifespan for flies living in the blue-LED light-dark cycles was as much as 50% shorter than the flies kept in total darkness.
The researchers then added a yellow filter to their light source to eliminate most of the blue light for the light-dark group. This scenario resulted in lifespans that were shortened by an average of only 4%.
“When we eliminated the blue light with a filter, but maintained the same overall light intensity, the flies lived much longer,” Giebultowicz says.
Because fruit flies have very large eyes, the team wondered if the brain damage and impact on lifespan were caused by the light entering the brain through the eyes. So they tried the experiment using mutant fruit flies that have no eyes. When these “eyes-absent” flies were exposed to light-dark cycles, lifespan was still shortened by 40%.
“Light is necessary for life, but extended exposure to artificial light appears to be damaging,” Giebultowicz says. “A lot is known about UV light and the damage it can do to skin, etc., but it is becoming increasingly clear that blue light might damage cells in a different way.”
The researchers also showed that blue light appeared to accelerate the aging process in fruit flies. The flies exposed to blue light climbed much more slowly up the inside of the enclosures, a possible indication of aging.
Giebultowicz is quick to point out that we don’t know the long-term effects of blue light on humans. Artificial blue light has not been around very long in an evolutionary sense, and the human brain would receive much less light than the brain of a fruit fly.
“But we can say that long-term exposure to blue light has a damaging effect on cells, and the cells in both humans and fruit flies function in a similar way,” she says.
Giebultowicz is collaborating with other OSU scientists to help advance the research. She is working with David A. Hendrix, a professor of computer science and biochemistry/biophysics, to use bioinformatics, the combination of biology, computer science, information engineering, mathematics and statistics to analyze and interpret biological data.
“We started with physiology and are now bringing in bioinformatics to more deeply analyze the data,” she says. “It’s kind of like a detective story, and we’re looking for more clues to see exactly how this blue light is causing mortality and what is happening at the cellular level that is contributing to all of this.”
From Warsaw to the Northwest
The first person in her family to attend college, Giebultowicz grew up in Poland, where she developed an interest in how biological clocks impact insect behavior. Her early work focused on small moths that can infest stored food supplies. She helped discover that long exposure to light caused infertility in male moths and could be used as an organic method of safeguarding food storage without using pesticides. Her graduate adviser suggested she seek an international education, so in 1981 Giebultowicz traveled to Seattle for a one-year, post-doctoral position at the University of Washington.
However, shortly after she left Warsaw, the rising Solidarity movement in Poland fell, and the Communist party took over, implementing widespread media censorship and other restrictive measures. Her husband, Tomasz Giebultowicz, was able to leave Poland and joined Jaga in Seattle, where they “fell in love with the Pacific Northwest.”
After Seattle, they moved to Washington, D.C., where their children were born and the couple worked for the next 12 years. In 1995, they were both offered faculty positions at OSU and were happy to return to the Northwest. Tomasz is now a retired faculty in the Department of Physics.
Tips to Reduce Exposure to Blue Light
Giebultowicz’s research has influenced her personal behavior. She has prescription glasses with amber-tinted lenses to help filter out the blue end of the spectrum. She adjusts the settings on her computer screen and cell phone to reduce emissions of blue light. And at home, she finds herself dimming the lights. She encourages her students and others to consider wearing amber glasses when working on computers and other digital devices.
Although the research is still in the early stages and artificial blue light hasn’t been around very long, the impacts on fruit flies might serve as an early warning for humans about an invisible danger — the way those bright yellow canaries served coal miners years ago.
Gregg Kleiner is a freelance writer in Corvallis, Oregon.