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How blue light affects health

In the present time, human interactions with digital devices such as smartphones, tablets and laptops is galloping everyday as people spend a lot of time scrolling and swiping on social media, watching movies and reading work reports on laptops or tracking financial or stock sales deals on computer desktops. So, without any doubt, most of us spend a lot of time staring at screens. And that can be bad for the eyes. Blue light from electronics is linked to problems like blurry vision, eyestrain, dry eye, macular degeneration, and cataracts. Some people have sleep issues. Here’s what you need to know.

 

What is blue light?

It’s one of several colours in the visible light spectrum. The others are: Red, orange, yellow, green, blue, indigo and violet. They are known by the acronym ROY G BIV. Together, they make the white light you see when the sun, the main source of blue light, is shining. Fluorescent and LED (light-emitting diode) light bulbs also give off blue light.

Each colour in the visible light spectrum has a different wavelength and energy level. Blue light has shorter wavelengths and higher energy than other colours. Some research shows a link between eye damage and short-wave blue light with wavelengths between 415 and 455 nanometers. Most of the light from the LEDs used in smartphones, TVs, and tablets has wavelengths between 400 and 490 nanometers.

 

Impact of blue light on the eyes

 

In large amounts, high-energy light from the sun, like ultraviolet rays and blue light, can boost your risk of eye disease. That’s raised concerns about whether blue light from digital screens is harmful. Research is ongoing to learn more and provide a definitive answer.

However, experts think that digital eyestrain or computer vision syndrome, affects about 50 per cent of computer users. Symptoms include dry, irritated eyes and blurred vision.

Blue light may also damage the retina. That’s called phototoxicity. The amount of damage depends on wavelength and exposure time. Animal studies show even short exposure (a few minutes to several hours) may be harmful. A filter that cuts 94 per cent of blue light has been shown to lessen damage.

There’s evidence blue light could lead to permanent vision changes. Almost all blue light passes straight through to the back of your retina. Some research has shown blue light may increase the risk of macular degeneration, a disease of the retina.

Research shows blue light exposure may lead to age-related macular degeneration, or AMD. One study found blue light triggered the release of toxic molecules in photoreceptor cells. This causes damage that may lead to AMD.

 

Blue light and sleep

Screen time, especially at night, is linked to poor sleep. The blue light from electronic devices messes with the circadian rhythm or sleep cycle. It signals your brain to wake up when it should be winding down. In one study, as little as two hours of exposure to blue light at night slowed or stopped release of the sleep hormone melatonin. Powering down your digital devices at least three hours before bedtime can help.

 

Blue light and cancer

Blue light exposure might raise your risk for certain cancers. One study found that people who work the night shift are at greater risk for breast, prostate, and colorectal cancers.

 

 Blue light and kids

The eyes of children do not filter blue light as well as adult eyes do. Too much of it from device screens may raise their chances of developing obesity, nearsightedness, and attention focusing issues. At night, it may cause their body to release melatonin even more slowly than it does yours. To protect their eyes, limit your child’s screen time. And have them put all electronic devices, including handheld game devices, away at least a half hour before bedtime.

 

Blue light and mental health

Night-time exposure to blue light was linked to depressive symptoms in animal studies. But exposure to blue light during the day may have the opposite effect. It’s been used to treat seasonal affective disorder, or SAD. That’s a form of depression related to the changing of the seasons. Research shows that 20 minutes of blue light exposure in the morning helps ease SAD symptoms.

 

• Adapted from webmd.com

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