Recent research has indicated that artificial light, especially blue light produced by LED lamps, is affecting the normal functioning of hormones, one of them, melatonin, responsible for regulating people’s sleep-wake cycles.
According to data from the International Agency for Research on Cancer (IARC), in Chile there are 55 cases of breast cancer per 100,000 women. It is also one of the cancers with the highest lethality, being the second cause of death in Chilean women according to data from the Ministry of Health.
Various studies worldwide have focused on identifying the causes of this disease. In recent years, researchers have discovered that there is a relationship between excess artificial light, especially that produced by LED lamps, and a higher risk of developing breast cancer.
Fundación Cielos de Chile is an organization dedicated to informing about the effects of light pollution and preventing its advance in the country. Daniela González, executive director of the foundation, warns about the impact this form of pollution is having on people’s health.
“There is scientific evidence that blue light is affecting people’s health with chronic diseases such as diabetes, hypertension, and obesity. The latest research indicates that it is an incidence factor in the development of breast cancer, even in people without a history,” explains Daniela.
Breast cancer and melatonin
In 2002, ipRGC cells, located in the retina, were discovered. These cells are the main sensor that our eyes have to regulate the production of melatonin, circadian rhythms, and the regulation of other non-visual systems. The ipRGC cells respond preferentially to blue light, so their functioning could be especially affected by modern artificial light.
Circadian rhythms regulate the changes in physical and mental characteristics that occur over 24 hours. They are controlled by our biological clock, which is located in a region of the brain called the hypothalamus. Signals from this area activate the pineal gland, which responds to the lack of sunlight by producing melatonin, a substance that helps us sleep.
Various studies have investigated the relationship between breast cancer and the alteration of these biological processes. For example, a 2015 study demonstrated that melatonin suppresses the development of breast cancer cells, thus preventing this disease. Other research has shown that patients with longer sleep duration have a higher concentration of melatonin and a lower risk of breast cancer. Meanwhile, a dozen studies have suggested that the alteration of circadian rhythms would be a cause of this disease.
How to prevent breast cancer
A 2021 study confirmed that there is a relationship between exposure to artificial night light and the risk of breast cancer. This association occurs at a general level, but is greater among young women. It has also been found that artificial night light can influence the duration of the menstrual cycle, which also implies a higher risk of breast cancer before menopause.
In this same line, a 2016 study confirmed that those who live near sources of artificial night light have a higher risk of developing breast cancer. However, this risk decreases with:
- Longer night sleep
- Less exposure to light coming from outside through the use of curtains and blinds.
- The habit of reading before sleeping.
“These investigations show us that light pollution is affecting people’s health, especially women. But it is important to keep in mind that this can be prevented without the need to return to darkness,” says Daniela González, executive director of Fundación Cielos de Chile.
According to the institution, there are three basic principles to illuminate our cities in a way that is friendly to the environment and people’s health:
- Direct the light to the target you want to illuminate through spotlights that point downwards.
- Control the intensity of the light so that it is no more than strictly necessary
- Prefer warm colors with low blue emissions content.
“Through these simple measures we can control the effects of light pollution on our health and the development of biodiversity,” concluded the executive director of Fundación Cielos de Chile.
