Myth or Truth: Does blue light actually hurt our eyes?


Our eyes are exposed to blue light every day. Many of us know that it is emitted from our digital devices and LED lights, but did you know that it is also emitted by the sun?

In fact, sunlight is the biggest source of blue light and until recently (before the Covid-19 pandemic, that is), we have been getting most of our exposure to it when we go outdoors during daylight.

Blue light is everywhere, and our eyes are constantly exposed to it. As such, is it really harmful to us? The short answer to this question is – it can be good and bad for us!

The dark implications of blue light

1. Digital eye strain

Prolonged blue light exposure may cause digital eye strain. How exactly does this happen?

When blue light enters our eyes, it scatters and increases the effort needed by our eyes to maintain focus. This increased effort may contribute to eye fatigue and eventually eye strain.

2. A poor night’s sleep

As it turns out, your screens may be to blame for a poor night’s sleep and the ensuing grogginess you have to deal with the next day.

More specifically, the blue light emitted from the screens of digital devices has been shown to cause significant disruptions to sleep. Research has shown that this blue light suppresses the production of melatonin, a hormone produced by the brain that helps induce sleep. 

The effects of this disruption can be likened to jet-lag: your sleep cycle is disrupted, and you find it difficult to fall and stay asleep at your usual times, and you may find yourself waking up more frequently at night. 

Startlingly, even small amounts of sleep deprivation have comparable effects on brain function to those of alcohol intoxication: In fact, a 17 – 19 hour period of no sleep (which may be the same as waking up at 7am and going to sleep at 1am which many of us do regularly) is equivalent to a blood alcohol concentration of 0.05%!

A never-ending cycle

Worse yet, research suggests that the lack of quality sleep causes your blink rate to slow. This decreases tear production and increases tear evaporation – leading to dry eye and more eye strain!

3. Macular degeneration

Macular degeneration, also known as age-related macular degeneration occurs when a small central portion of the retina, i.e. the macula, wears down. This in turn affects visual acuity, or the sharpness of the eye. Exposure to blue light may increase the risk of macular degeneration. How?

Image via All About Vision

Our eyes are unable to prevent blue light from penetrating through the cornea and lens and into the retina. As such, excessive and prolonged blue light exposure can damage the light-sensitive retinal cells.

On the ‘bright’ side

Before you swear off sunlight and all other sources of blue light for good, it is important to note that blue light does have some benefits as well!

Exposure to blue light during daytime can improve energy and alertness, boosts your mood and your productivity. Beyond that, it helps regulate your body’s circadian rhythm or body clock, which helps you stay awake during the day and go to sleep at night.

A higher exposure to blue light in the day causes your brain to secrete less melatonin during daylight. And as it gets progressively darker, closer to bedtime, melatonin production increases. This makes you sleepy and signals to you that it is time to go to bed and get a good night’s sleep.

As with many things in life, blue light can be beneficial and detrimental to us. It is up to us to protect our eyes from the potential risks of prolonged and excessive blue light exposure. While it is important to recognise that more research has to be done in this space, it does not hurt to work on developing a well-balanced and healthy relationship with the screens that surround you on a daily basis!

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