Too much artificial light can suppress melatonin production at night

Artificial light can also cause damage to the human body with regard to the production of melatonin at night. A team of researchers from the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), supported by other international researchers, have carried out a new study on the impact of light pollution.

It is already known that melatonin is one of the substances responsible for the so-called circadian clock, a sort of internal clock that regulates many of our natural processes. Researchers have discovered that artificial light, even the glow of evening and night lights in the sky, can cause damage to the very formation of melatonin, and this happens to both humans and vertebrates.

Melatonin, in fact, synchronizes the day-night rhythm and can regulate the various versions of the aforesaid circadian clock that are in the body and that can refer to various tissues, organs, groups of cells, etc. The researchers started from the assumption that in vertebrates the so-called photoreceptors, which are found in the retina, detect differences in light levels and when the light exceeds a certain level the same production of melatonin is suppressed.

Analyzing 72 previous studies on this topic, the researchers came to the conclusion that even rather low light levels can suppress this important production in some vertebrates. The most susceptible ones are fish that, once a threshold of 0.01 lux is exceeded, already begin to experience an interruption in melatonin production. They are followed by rodents with a level of 0.03 lux. The limit for humans is set by researchers at 6 lux.

According to the researchers, even artificial light reflected in the night sky (e.g. from clouds and various particles, something also called “Skyglow”) is sufficient to suppress the production of melatonin in several vertebrates, as explained by Maja Grubisic, one of the researchers who produced the study.

According to Franz Hölker, another researcher involved in the study, the impacts of light pollution and decreased melatonin production on human health have never really been understood.

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