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Switching off before nodding off- the affects of blue light

Woman on her laptop laying on her bed at nighttime
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We’ve all been hearing about blue light recently, from blue light filtering glasses to digital screens and sleep patterns. But what is blue light? Where do we get it from and how does it affect us? We’ve got the answers.

What is blue light?

Blue light is part of the visible light spectrum emitted from the sun. Out of all the light waves, blue light has a shorter wavelength and higher energy. They get bounced around the most by molecules in the Earth’s atmosphere and are the reason for the sky being blue.

What are common sources of blue light?

Blue light can be emitted from many different sources, the largest of which is the sun. Computers, tablets, smartphones and digital screens also all emit blue light. Although on a sunny afternoon, natural sunlight is almost 100,000 times brighter than a computer screen, with our increased use of phones and digital screens it’s important to be aware of the affect that blue light can have.

How will blue light affect me?

During the daytime blue light is beneficial, the blue light wavelengths can boost attention, reaction times and mood.

Because blue light has a short wavelength, it passes through the eye to the retina. Some studies have shown that over exposure to intense blue light has damaged the cells in the retina of mice which has led some people being concerned about the blue light emitted from our computers, phones and other digital screens. But human eyes are different to rodent eyes and ours contain protective elements. We are also used to blue light from the sun which is much stronger than blue light from a screen. Some people have been opting for blue light filtering glasses but there has been no research to suggest that they can protect or improve our eye health.

If you are feeling eye strain from looking at a screen all day it could be because we don’t just look at a computer screen, we stare. Our blink rate decreases from 12 blinks a minute to 6 and our tears evaporate from the surface of the eye. Some optometrists advise taking a 20 second break every 20 minutes to look at something 20 feet in the distance. This will allow your eyes to blink and relax. It’s also worth ensuring you’re regularly visiting the optician to get your eyes checked over.

Although blue light might not be affecting our eyes, it does have an impact on our sleep.

We all have our own internal body clocks (circadian rhythms) These rhythms control our sleep cycles, tell our bodies when to be awake, look after our body temperature, hunger, mood and hormones. 

Using screens at night and just before bedtime can affect our circadian rhythms. Exposure to light at bedtime can shift our body clock and affect the quality of our sleep.

How can I minimise the impact of blue light?

The best way to minimise the impact of blue light at night-time is to switch off electrical devices an hour before bedtime. You could try reading a book, listening to a podcast with the screen switched off, some gentle yoga or practise mindfulness. How you choose to relax and switch off is up to you but make sure you’re minimising your time in front of a screen. You could also increase your exposure to daylight during the day by going for a walk at lunch time. 


www.optometrists.org/general-practice-optometry/blue-light-and-screens/ www.specsavers.co.uk/glasses/glasses-lenses/do-blue-light-glasses-work