Research suggests that 80% of the world’s population lives under ‘skyglow’, and it is becoming increasingly rare to view a natural night sky unhindered by light pollution. This article will look at light-emitting diodes (LEDs) and their consequences on the environment and animal health.
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LED Lights are Increasing Global Light Pollution and Harming the Environment
Artificial light disturbs the natural light/dark cycle of the world. Animals and plants evolved over millennia, responding to the natural daily transition from dark to light and back to dark again. As a result, humans and plants have developed circadian rhythms that are in tune with this cycle.
LEDs disturb this cycle. They introduce a source of light in the hours of darkness. From 2012 to 2016, the world brightened by 2% annually. This is concerning for scientists, as light pollution has significant implications for the health of ecosystems.
Introducing light during the night disturbs the evolved life-sustaining behaviors of animals, such as reproduction, nourishment, sleep, and protection from predators. Studies have shown that light pollution negatively impacts bats, birds, insects, reptiles, amphibians, mammals, and plants.
Light pollution is known to impact the flight paths of migratory birds as it confuses their flight trajectories. This can lead to crashes and fatalities. Another example is of the effect of light pollution on sea turtles. These animals live in the ocean but hatch on the beach at night. Once hatched, the turtles navigate toward the sea by detecting the horizon's light over the ocean. Artificial lights, such as LEDs, confuse them, often drawing them in the wrong direction. As a result, millions of turtle hatchlings die each year.
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LEDs are a significant source of light pollution as they are often used in outdoor displays. These digital displays often rely on blue LEDs, which are particularly harmful to animal behavior due to their impact on melatonin. Recent research using imagery captured from the International Space Station has found that Europe has shifted from old orange-hued lights from older sodium bulbs to white-colored lights produced by LEDs. This represents a major problem given the impact of LEDs on the environment.
Melatonin Production is Suppressed by LEDs, Causing Sleep Disturbance
In the darkness, the mammalian pineal gland is prompted to produce melatonin, the hormone that regulates the sleep-wake cycle, helping us transition from wakefulness to sleep. Artificial light disturbs melatonin production, with LEDs being a particularly harmful disrupter.
LEDs are used in screens and electronic devices such as televisions, laptops, tablets and smartphones. These devices are increasingly used by the population, increasing our exposure to LED light. Exposure to this artificial light at night can cause sleep problems due to its impact on melatonin. Specific LED colors can be more harmful than others.
Blue LED light, commonly used in displays (such as laptops and phones), has a greater impact on melatonin suppression than red LED light. Studies have shown that blue LED light significantly impacts melatonin suppression, which prevents sleepiness. Blue light is the type of light produced by natural sunlight, therefore, it is associated with wakefulness. It boosts our attention, reaction times, and mood. However, at night, it tricks our bodies into believing we should stay awake rather than rest.
It is problematic that blue LEDs have become part of our everyday lives as they are incorporated into our much-depended devices. Red lights, however, have been shown to encourage melatonin production and have been increasingly included in products such as alarm clocks and night lights.
The Role of Melatonin in Disease
Melatonin plays a vital role in disease, particularly in cancer. Studies suggest that disruption to melatonin production may allow cancer to develop, and further studies have shown that reduced melatonin levels may allow cancer to grow.
Research has demonstrated that impaired melatonin production can cause various pathophysiological changes that can facilitate cancer development. Low melatonin levels have increased breast, colon, ovarian, and prostate cancer risk.
Melatonin may play an essential role in fighting cancer. Research has highlighted the involvement of melatonin in various anti-cancer mechanisms, such as apoptosis induction, cell proliferation inhibition, reduction in the growth of tumors and metastases, reduction in chemotherapy and radiotherapy-associated side effects, and reduced resistance to cancer treatment.
LEDs' role on the environment and health must be fully understood to prevent these negative effects. For example, employees who work night shifts are likely to face long-term exposure to LEDs in the hours of darkness. This may increase their risk of sleep disorders and cancer via disruption to melatonin production. Further research will likely develop our understanding of these relationships, allowing us to implement effective preventative strategies.
Read More: How Does Light Pollution Affect Birds?
References and Further Reading
Das, N. and Samanta, S. (2022) The potential anti-cancer effects of melatonin on breast cancer. Exploration of Medicine, pp.112-127. https://www.explorationpub.com/Journals/em/Article/100178
Falchi, F., Cinzano, P., Elvidge, C., Keith, D. and Haim, A. (2011) Limiting the impact of light pollution on human health, environment and stellar visibility. Journal of Environmental Management, 92(10), pp.2714-2722. https://www.sciencedirect.com/science/article/pii/S030147971100226X
Sánchez de Miguel, A., Bennie, J., Rosenfeld, E., Dzurjak, S. and Gaston, K. (2022) Environmental risks from artificial nighttime lighting widespread and increasing across Europe. Science Advances, 8(37). https://www.science.org/doi/10.1126/sciadv.abl6891
Sroykham, W. and Wongsawat, Y. (2013) Effects of LED-backlit computer screen and emotional selfregulation on human melatonin production. 2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC),. https://pubmed.ncbi.nlm.nih.gov/24110034/
Talib, W., Alsayed, A., Abuawad, A., Daoud, S. and Mahmod, A. (2021) Melatonin in Cancer Treatment: Current Knowledge and Future Opportunities. Molecules, 26(9), p.2506. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8123278/
Wang, L., Wang, C. and Choi, W. (2022) Use of Melatonin in Cancer Treatment: Where Are We?. International Journal of Molecular Sciences, 23(7), p.3779. https://www.mdpi.com/1422-0067/23/7/3779/htm
Waseem, Mohamed. (2022) Increase in LED lighting ‘risks harming human and animal health’ [online]. The Guardian. Available at: https://www.theguardian.com/environment/2022/sep/14/increase-in-led-lighting-risks-harming-human-and-animal-health
Zisapel, N. (2018) New perspectives on the role of melatonin in human sleep, circadian rhythms and their regulation. British Journal of Pharmacology, 175(16), pp.3190-3199. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6057895/