Over the last decade, most of Europe and the United States have modified the way they illuminate city and town streets.
Councils and local governments from Paris to Brooklyn have replaced high-energy sodium lights (the warmer, yellow ones) with energy-saving LED lamps (with a blue light emitting diode, which can feel harsh in comparison). In addition to street lights, most of us are exposed to blue light through cellphones, laptops, televisions, and other devices in our homes.
Although this was done to address the pressing need to use less energy and cut carbon emissions - LED lights are more energy-efficient - there are growing worries that LED lights may have a harmful impact on human health that we do not yet completely understand. At the same time as early blue LED lights were being commercialized, there was a breakthrough in our understanding of the eye. The photopigment melanopsin was discovered in the 1990s, explaining how light penetrates the eye and why blue light inhibits melatonin synthesis. Melanopsin-containing cells are highly sensitive to blue light, and melanopsin is critical in establishing circadian rhythms.As a result, blue LEDs create an increase in alertness and interfere with sleep habits in both people and animals.
The World Journal of Biological Psychiatry released an article earlier this year by a group of notable psychiatrists warning of the possible consequences of LED lighting on mental disease.
It highlighted concerns about the impact of blue light on sleep and other circadian-mediated symptoms, the usage of digital healthcare applications and gadgets, and teens' increased susceptibility to blue light.
“My concern about LED lighting followed from a larger, earlier concern about the relationship between light exposure and the occurrence of manic and mixed symptoms in bipolar disorder,” explained John Gottlieb, Clinical Assistant Professor of Psychiatry and Behavioral Sciences at Feinberg School of Medicine in Chicago and one of the paper's authors.
“I had already clearly seen that supplemental light exposure - in the form of bright light therapy - was extremely helpful to patients with depression. What I was slower to realize was that excess and poorly-timed light exposure could have adverse effects on manic states and the sleep-wake cycle,” he explained.
The work has ramifications for mental disease therapy. If a person is prescribed a self-monitoring app and encouraged to use their smartphone to document mood changes, for example, and they do so before bed, it might disrupt their sleep, circadian rhythms and health.
“Because they are ubiquitous, smartphones represent the larger public health hazard,” Gottlieb added. “Streetlights, though, are not benign and together with the entire set of nocturnal lighting for entertainment, traffic, reading, etc contribute to the phenomena of light pollution, which we are becoming increasingly sensitised to.”
Blue light has been shown in studies to block melatonin release, which interrupts sleep and can influence quality of life, physical and mental health, and susceptibility to sickness. Previous research on sleep problems in children and teenagers has found a strong and continuous link between sleep disorders and the frequency with which digital devices are used.
The National Sleep Foundation now recommends avoiding using technology 30 minutes before bed and eliminating gadgets from the bedroom. There are presently no particular guidelines for persons who have a mental condition or are sensitive to circadian disturbance.
As LED technology has grown fast throughout the world, the emphasis has been on the aesthetic and energy-saving aspects. Scientists, health experts, and the LED industry are now collaborating to reduce blue light in LEDs and build configurable lights that will not affect persons with psychiatric problems.