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Home Latest Articles PC Monitors Kagoo Explains: Light Part 2 - Blue Light

Kagoo Explains: Light Part 2 - Blue Light

Updated 21 October 2020
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Welcome to ‘Kagoo Explains’ - a series of short articles de-mystifying some of the confusing terminology used to describe tech. Following on from our article on Colour Temperature, today we’ll be looking at blue light, and the problems attached to it.

In recent years, a lot has been written about the downsides of a life spent sitting in front of a screen. Bad posture and lack of mobility are frequent complaints, but the number one trouble is eye strain. Staring at a screen for long periods without a break can cause eye strain, headaches, and may contribute to long term retina damage. Given how crucial screens are to our everyday life, it’s more important than ever to understand and protect against such problems.

What is blue light?

Before we can see how to combat blue light, we first have to understand what it is. We explain light in more depth in our article on Colour Temperature, but in brief: what we call ‘light’ is actually a kind of electromagnetic radiation, which exists as part of a broad spectrum - all with different wavelengths (i.e - how ‘fast’ the specific wave moves).

On the very lowest end of the spectrum are radio waves, which are used for communication and transmission, and up the very top we have x-rays and superpower-giving gamma rays. ‘Light’ sits approximately in the middle of this spectrum.

The wavelengths that make up light are split into 2 categories - visible and invisible. The visible light allows us to see, while the invisible portion contains UV (ultraviolet) light. Blue light sits on the boundary between the visible and the invisible.


Now, blue light exists everywhere: the rays from the sun give off blue light, so you are soaking in it for most of the day. This is both expected and healthy for the body. However man-made displays also give off large amounts of blue light, and people are viewing these screens (TVs, PC monitors, phones, etc) for longer and longer periods every day. It is long-term exposure to this concentration of blue light that carries potential health issues.

Health problems concerning blue light

There are 3 major concerns connected to excessive amounts of blue light:

1 - Macular Degeneration: Worryingly, excessive blue light may contribute to gradual blindness. While the human eye is very good at at blocking harmful rays (less than 1% of harmful UV radiation penetrates the eye), blue light circumvents this protection, passing all the way to the retina. Scientific studies (FIND LINK) suggest that exposing the retina to significant amounts of blue light damages the light-sensitive cells inside the eye. This leads to increased deterioration of the ‘mascula’, causing accelerated vision loss.

2 - Digital Eye Strain: The concentrated amounts of blue light in computers and mobile devices can also cause a number of short term problems, which all come under the banner of ‘Digital Eye Strain’. Symptoms include headaches, irritated and dry eyes, blurred vision and muscle pain.

3 - Upset Circadian Rhythm: Finally, excessive blue light can upset the body’s natural sleep-wake cycle, known as the ‘Circadian Rhythm’. This cycle tells your body when it needs to sleep, and when it needs to be awake and alert. As mentioned above, blue light is found naturally in sunlight - the body uses it as a signal that it is daytime, and so you need to be awake. Which is all well and good… until the body receives blue light late at night, say from a phone screen or TV. This inadvertently tricks the body into thinking it’s still daytime, and it suppresses the flow of melatonin, which helps you get to sleep. This is why it’s a good idea to avoid using your smartphone for at least 30 minutes before you get to sleep.


As you can see, the concerns of excessive blue light range from minor annoyances to life-changing health problems. Therefore it’s best to be careful, and try and mitigate your blue light exposure where possible.

Protecting against blue light

So how can you prevent messed up sleep patterns and long-term trouble to your eyes? There are several methods to reducing your exposure to blue light:

  • Use a blue light filter mode on your monitor or phone. Most modern mobile phones and monitors have a special setting to lessen the amount of blue light given off by the screen. They do this by altering the colours displayed on the screen, moving them away from blue towards the yellow-brown end of the spectrum. This change in colour balance reduces blue light emissions from the screen.
  • Use night mode on your phone. Both Android and iOS have a ‘late night’ or ‘night’ mode, which not only shifts the colours on the screen away from blue, but also reduces the brightness and contrast - this serves to limit the negative effect on the body’s circadian rhythm, maximising melatonin production for a better night’s sleep.
  • Invest in a pair of special blue light glasses that act as a constant filter to reduce blue light reaching your eyes.
  • Reduce the amount of time you’re looking at a screen, and take frequent breaks. Ideally stop looking at any screens (especially your phone) for at least an hour before bed.
  • If you have to use the computer for extended periods, don’t just stare at the screen unblinkingly. The ‘20-20-20’ rule is a good rhythm to adopt - after every 20 minutes of staring at a screen, take a moment to look at something 20 feet away for at least 20 seconds.

We’re aware it can be very easy to suggest such sweeping changes, but very difficult to actually implement them, especially when fiddling with Instagram late at night is such a muscle memory. However even a small change in your exposure to blue light can help your eyes in the long-term, so it’s an effort worth making.

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