What is blue light? How does it affect us?
In recent years, there has been increasing talk about the damage that light can cause to vision. On the one hand, there is concern about exposure to ultraviolet light, as it is causing an increasing incidence of sunburns, skin cancer, and so on. On the other hand, the widespread use of light bulbs and digital devices that emit blue light is being studied and discussed.
The light spectrum contains light frequencies invisible to the human eye, such as microwaves, radio waves, and X-rays, among others. Some of these are harmful to our health. The visible spectrum contains a very small portion of wavelengths, specifically between 380 nm and 780 nm. The blue light spectrum is just above the ultraviolet and is a high-energy light range. This light is scattered by the atmosphere and is the reason we see the sky blue.
This blue light is produced by the sun, but also by LEDs, which are very common today. Due to the efficiency of LEDs, traditional incandescent bulbs have been replaced. Furthermore, this type of lighting is found in digital technologies such as televisions, phones, and tablets for commercial use. As the use of digital devices increases, so does the transmission of light to the eyes.
Regarding eye health, it has long been known that blue light can be harmful to certain ocular structures. Eye protection is especially important in children because light transmission is highest at a young age. This allows higher levels of UV and blue light to reach the lens and retina.
Several studies have shown that the retina is at greater risk of developing pathologies due to excessive exposure to blue light. Specifically, the cumulative effect of blue light has been identified as a risk factor. Furthermore, excessive exposure to blue light has been shown to interfere with the quality of our sleep. The use of digital devices can wreak havoc on sleep patterns by interfering with human circadian rhythms.
As we stop being exposed to blue light during the day, retinal ganglion cells stimulate the pineal gland to produce melatonin (the hormone that lets our body know it's time to sleep). If we use digital devices, what happens is that the continued exposure to blue light suppresses melatonin production, causing our bodies to become alert and energized, making us unable to fall asleep.