The subject of blue light and its effect on the human body has been a topic of contention among the scientific community for decades. Blue light, which is a form of electromagnetic radiation composed of microscopic clots of strong energy called photons, is the type of light that the sun emits on a cloudless day. Despite its natural origins, many scientists argue that blue light is not safe for humans.
One of the main concerns regarding blue light is its potential to cause rapid aging of the eyes. As we learned in our physics course, light travels in waves, and each element of the color spectrum has a different length measured in nanometers (nm). Red, which is located at the beginning of the visible spectrum, has a wavelength of 620-770 nm and is easily perceived by the human eye. Blue, on the other hand, has a much smaller wavelength and higher energy, penetrating deeply into the eye and causing significant fatigue, which may not always have a beneficial effect on the body.
Despite the importance of light in providing the synthesis of many vital organic substances, such as vitamin D, exposure to blue light at night is a cause for concern. With the widespread use of electric lighting for over a century, most lights now emit purple, blue, and blue wavelengths, which fall within the HEV (High-energy visible light) spectrum. This radiation is emitted by almost all energy-saving lamps, LED lighting in offices and apartments, the displays of smartphones, tablets, and electronic books, as well as modern televisions and car dashboards. It is estimated that 60% of people spend more than 6 hours a day with mobile devices, exposing themselves to prolonged exposure to blue light.
Studies conducted as early as 1971 by American ophthalmologists have found that prolonged exposure to blue light leads to the loss of spectral sensitivity, which may result in damage to the retina. This finding was confirmed by experimental studies conducted on primates in the 1980s in Japan. Scientists from the University of Tokyo found that after exposure to blue light, there was massive cell death in the retina. In the 2010s, Professor Ajit Karunaratne of the State Research University in Toledo, Ohio, USA, proved that the same happens in humans. Exposure to blue light for eight hours a day for four to five years is enough to initiate irreversible changes in the retina, which can lead to maculopathy, a form of pathology that affects the central zone of the retina, resulting in the distortion of perceived images and loss of vision. Even young people with normal vision who are exposed to blue light sources for prolonged periods can develop these symptoms, which are typically associated with elderly individuals who have been exposed to normal daily sunlight for forty years or more.
The intricate relationship between the development of diabetes and obesity has been a topic of much research in recent years. One noteworthy study, conducted by American researchers at Harvard University, delved into the link between weight gain and night shifts, revealing the profound impact that working during unconventional hours can have on the human body.
According to the study's findings, the human body's circadian rhythms - cyclical fluctuations of biological processes caused by changes in day and night - are disrupted by the constant work at night shifts, leading to a variety of health issues. The researchers put dozens of volunteers through a unique experiment in which they were asked to work their regular professional duties at midnight, a time when the room was lit with blue light. The results were startling.
Within just one week, blood and hormone tests of the subjects showed initial signs of abnormality. After a month, it was discovered that blood sugar levels in these workers had increased significantly, with four out of ten people becoming almost pre-diabetic. Levels of the hormone leptin, which is responsible for the feeling of satiety after a meal, dropped in all of the volunteers, leading to constant hunger pangs, even after eating.
What causes such dramatic changes in the body's systems? The researchers theorized that a lack of the hormone melatonin could be responsible. Discovered in the mid-20th century, melatonin is the primary hormone of the epiphysis, an organ in the brain that communicates information about the light environment to the body's internal environment. Blue light, detected through visual receptors, suppresses its synthesis, thereby destabilizing the entire endocrine system. At first, this disorder manifests itself in the form of minor weight gain. Over time, however, it can lead to obesity, even in otherwise healthy individuals. In some cases, this disruption of circadian rhythms can lead to latent diabetes.
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