What Is Blue Light?
Blue light comes under the visible spectrum that a human eye can visualize. As the name indicates, this type of light is recognized as blue. However, blue light may be present in lights that are identified as white or another color. About one-third of all visible light is observed as blue light. The human eye is responsive to a particular segment of the electromagnetic spectrum, known as light.
Other segments of the electromagnetic spectrum that the human eye cannot visualize are known as radiation. The visible light spectrum to the human eye includes wavelengths ranging from approximately 380 nm (nanometers) to 780 nm. Blue light comes under the human visible spectrum of wavelengths between 380 nm and 500 nm. This is the shortest wavelength in the visible light spectrum.
Natural blue light can be found all day long, as it is a segment of the light spectrum emitted by the sun. Before the light bulb invention, the human eye was only exposed to blue light all day, from sunrise to evening. In modern times, people are surrounded by various sources of artificial blue lights, including LED TVs, fluorescent lights, smartphones, computer monitors, and tablet screens.
And modern light sources emit a relatively higher proportion of blue light. So these days, human eyes are exposed to blue light much longer than in the past, especially at night. Blue light is of main concern as it has more energy per photon of light than other visible spectrum colors, such as green or red. When human eyes are exposed to blue light in high doses, it can be absorbed by various cells in the body and cause damage.
How Does Blue Light Affect Human Eyes?
The amount of blue light exposure from screens is relatively small compared to the amount of sun exposure. However, long-term screen exposure from digital devices can be a concern, especially when individuals are involved in too much screen time and screens are too close to their eyes.
Human eyes are equipped with structures that protect them from certain types of light. The cornea (the transparent outer covering of the eye) and lens protect the light-sensitive retina (innermost, light-sensitive layer) at the back of the eye from harmful UV rays. Those structures do not keep the blue light away. In large amounts, high-energy blue light and ultraviolet light from the sun can increase the risk of eye disease. The natural blue light source can far exceed the amount from any individual device. However, health experts have raised concerns about blue light exposure from digital screens and devices, as most people spend a long time using electrical devices that emit blue light at such a close range.
Experts believe that digital eye strain, or computer vision syndrome, can affect more than 50 percent of computer users, causing symptoms like dry eyes, inflamed eyes, and blurred vision. Damage to the retina, called phototoxicity, can occur due to prolonged exposure to blue light. This is because human eyes are not good at blocking blue light, so all the visible blue light passes through the cornea and lens and reaches the inner part of the eyes, called the retina. The cells in the retina convert light to the brain and process it into pictures.
Constant blue light exposure over time could damage the cells of the retina and cause eyesight problems such as cataracts, eye cancer, age-related macular degeneration, and growths over the white part of the eye. Also, a study conducted by the National Eye Institute says that children are more prone to blue light risk than adults, as their eyes absorb more blue light from digital devices. Additionally, when using digital devices, people tend to blink less, which can cause dry eyes and eye strain. Eye strain can also lead to many other signs, including blurred vision, headaches, and neck and shoulder pain.
How Does Blue Light Affect Sleep?
Our body has many light sensors in the eyes and skin. It can perceive the difference between intense and bright daylight and the warmer and redder tones of light in the evening. When the sunlight hits, the bright blue light will reduce and become dark, and then the sensors in the eyes prepare the body to release melatonin, the sleep-inducing hormone that induces sleep. However, exposure to high blue light from electronic devices can mess up their circadian rhythm or sleep cycle and signal the brain to be alert when it should be winding down. A study has revealed that when people are exposed to as little as two hours of blue light in the evening, their bodies may not release the required melatonin, and their sleep cycles can be disrupted.
How to Reduce the Negative Effects of Blue Light?
It is necessary to limit the use of blue light to reduce its adverse effects:
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If individuals are working with a digital screen for a prolonged duration, they must practice the 20-20-20 rule to reduce eye strain. Stop every 20 minutes and take a 20-second break to view some objects 20 feet away.
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Get blue-light filters for the computer screen, smartphone, and tablet. These filters block 30 to 60 percent of the blue light from reaching the eyes without affecting the display's visibility. Or use blue-blocking glasses that are effective at reducing blue light. However, whether blocking the blue light will help preserve the sleep-wake cycle is unclear.
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Set up a good distance from the screen for working and maintain an effective posture for screen viewing. Correct all minor vision problems to avoid any vision issues.
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Do not let the eye become dry. Use eye drops and room humidifiers, which may aid in keeping the eyes moist and reduce irritation, while using blue-light-emitting devices.
Conclusion
Blue light is a part of the natural light spectrum. Generally, every individual is exposed to blue light from the sun. Artificial sources of blue light include lights from electronic devices such as computer screens, tablets, mobile phones, etc. Health experts suggest that artificial blue light could be damaging to the eyes. Blue light can also interfere with the sleeping cycle and cause a lack of sleep. So, it is advised to limit screen time during the night.
