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After analyzing an extensive amount of studies within a literature review, a team of researchers found that production of melatonin, which sets the internal clock for sleep, could be impacted by light pollution in both humans and animals. The results were published in the journal Sustainability.
The team, from Leibniz-Institute of Freshwater Ecology and Inland Fisheries, examined a literature review comprising of 1,900 studies on how melatonin production could be affected by artificial light.
Based on the findings, researchers determined that melatonin production could be abated by very low illuminance levels.
“Artificial light at night (ALAN) is increasing exponentially worldwide, accelerated by the transition to new efficient lighting technologies,” the findings state. “However, ALAN and resulting light pollution can cause unintended physiological consequences.”
“We identified studies on melatonin under typical light-polluted conditions in fishes, amphibians, reptiles, birds, and mammals, including humans. Melatonin is suppressed by extremely low light intensities in many vertebrates, ranging from 0.01–0.03 lx for fishes and rodents to 6 lx for sensitive humans. Even lower, wavelength-dependent intensities are implied by some studies and require rigorous testing in ecological contexts,” according to researchers.
“In many studies, melatonin suppression occurs at the minimum light levels tested, and, in better-studied groups, melatonin suppression is reported to occur at lower light levels. We identify major research gaps and conclude that, for most groups, crucial information is lacking.”
Of all the studies examined, none involved reptiles or amphibians, researchers note.
“No studies were identified for amphibians and reptiles and long-term impacts of low-level ALAN exposure are unknown,” the study indicated.
“Given the high sensitivity of vertebrate melatonin production to ALAN and the paucity of available information, it is crucial to research impacts of ALAN further in order to inform effective mitigation strategies for human health and the wellbeing and fitness of vertebrates in natural ecosystems,” researchers concluded.