Electronic devices and their blue light impact

Have you ever thought about how much blue light you are exposed to on a daily basis? Blue light is everywhere: it is found in sunlight, some fluorescent lighting, some LED lighting, televisions, computer screens, phones, tablets, and game consoles.
Below we explain the effects of blue light, and how you can reduce blue light on iOS, Android and Windows devices.

This blog was written in collaboration with visually impaired author Simon Mahoney.

What are the effects of blue light?

There is contradictory research regarding the damage blue light can have on the eyes. Some research suggests that blue light can have a number of effects on the eyes, especially if the blue light is high energy, such as blue light emitted by the sun. It can cause dry eyes, cataracts and Macular Degeneration.

An American study has found that fluorescent lighting operating in the cool or blue spectrum can cause damage to the eyes of young children. In addition, it can cause further damage to eyes with existing conditions.

Blue light penetrates right to the back of the eye with little or no dispersal. This is more so in the case of small children. It impacts each photo-receptor in the retina with frequent bursts of high energy. The photo-receptors fire at the peak of every wave of light, the short wave blue light means that they are firing very frequently. This in itself is not problematic. what is a problem is that for every burst of activity, there is a unit of waste produced.

With short wave light, the waste disposal system of the eyes is unable to keep up. The eyes become clogged with waste. This produces blurriness and in some cases can cause lasting damage to the retina.

The frequent impact of high-energy bursts of light on the retina can result in the production of toxic molecules which can also cause deterioration in sight and in some cases permanent damage.

Much of the research is in its early stages. In some senses, the evidence about blue light is regarded with some scepticism. Harvard University has gone so far as to state there is no evidence to demonstrate that blue light is harmful.

The blue light in sunlight and the blue light emitted from electronic devices are very different, and there is no concrete evidence to prove that blue light from electronic devices causes damage to eye tissue. Research shows that blue light only causes damaging effects if the light energy is 3 microwatts or greater – most electronic devices typically emit light energy no greater than 1 microwatt.
Blue light can affect sleep. Blue light can prevent the production and release of the sleep hormone melatonin. Melatonin aids sleep and its absence can cause sleeplessness. Harvard University recommends that all devices emitting blue light should be turned off at least two hours before bedtime. Good luck with that!

As sleep is one of the most valuable restoratives, this can also have harmful effects on growth and general development. Other findings have found that blue light can cause both obesity and depression.

There are settings on electronic devices you can adjust to filter some of the blue light, and reduce the levels of blue light that are emitted.

Below, we explain how to adjust the blue light settings on iOS, Android and Windows.

How do I change the settings on my device?


Open Settings, select Display and Brightness, and then select Night Shift.

Within the Night Shift settings, you can adjust the warmth of the colours of your display – the warmer the colours, the less blue light. If using VoiceOver, the options are labelled ‘coolest’, ‘cooler’, ‘normal’, ‘warmer’, and ‘warmest’ and are adjusted by swiping up and down with one finger once you have navigated to the slider.

You can customise when the feature is enabled (between two specific times) or from sunset to sunrise.


Open Settings, select Display, and then select Eye Comfort Shield. Within the Eye Comfort Shield screen, you can adjust the colour temperature.

Microsoft Windows

Open Settings, select System, and then select Display.

Within Display, there is a button to toggle Night Light on and off, and a Night Light Settings option which enables you to adjust the colour strength and schedule when Night Light is turned on and off.

How can I find out more?

If you would like to learn more about blue light, watch our video below.

Further Reading

Ultra-violet and Blue Light worsen Macular Degeneration

Will blue light from electronic devices increase my risk of macular degeneration and blindness?

How Blue Light Affects Sleep

Blue Light and High Energy Visible Light | Effects on eyes

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