EFFECTS OF LIGHT POLLUTION ON HUMAN HEALTH
In a previous post we explained the environmental effects caused by light pollution. We may think that humans, comfortably enjoying our technological and social advances, are exempt from suffering the problems caused by excessive night-time light in our environment, but this is not really the case, as our physiology, like that of many other species, is also adapted to the 24-hour circadian cycle, which involves a succession of natural light during the day and darkness at night. This cycle has been profoundly altered over the last 50 years due to the massive introduction of artificial light sources.
The human body works differently depending on the type of light our eyes receive: during the day, the blue light from the sky that reaches our eyes inhibits the production of the hormone melatonin, which makes us feel active, and when the sunlight begins to fade, as the eyes stop receiving this blue light, melatonin secretion begins, inducing a state of relaxation prior to the sensation of sleep.
The imbalance that has occurred over the last few decades occurs when our eyes receive white light from artificial sources at night; this light contains an enormous amount of blue light, as it is not possible to generate white light without it containing a blue light component in its nature. This leads to a disruption of the circadian rhythm by changing the natural pattern of melatonin secretion.
Artificially extending daylight hours by using whitish light sources leads to alterations in our organism, the most benign of which is insomnia and its associated consequences (tiredness, irritability, headaches, etc.), but which can end up being aggravated to the point of causing different types of cancer (prostate cancer in men and breast cancer in women).
For people, exposure to artificial light at night does not only come from street lighting: in recent years, we have chosen to illuminate the inside of our homes with LED bulbs which often emit an excessively white light, with the consequences described above. The situation is not improved by being surrounded by all kinds of screens (mobiles, tablets, computers, televisions), which further aggravate the problem. It is no coincidence that there has been a recent proliferation of pharmaceutical products containing melatonin to compensate for the problems caused in our bodies by the pollution caused by artificial light.