How Does Blue Light Affect Sleep

What is blue light? Where does it come from? Why does blue light affect sleep? Many poor sleepers have been asking these questions. To what extent do screens and modern technology interrupt getting a good night’s rest? There is plenty of evidence that browsing social media on our phones or reading from e-readers, rather than a well-thumbed paperback, doesn’t help tired eyes. it is, however, not always clear why.

This article is designed to share answers to the above. It explores the effects of exposure to electrical devices at night. What does it do to your brain? Why is blue light bad for you? You’ll find answers from experts in our short guide.

Blue Light and Sleep

Our eyes see different light wavelengths as different colours. You will be familiar with the rainbow: red, orange, yellow and so on. Rainbows exist because sunlight is filtered into separate wavelengths by water in the atmosphere.

Blue light has a short wavelength. This means its waves have a higher amplitude and more energy than other colours. In fact, it is also known as high-energy visible (HEV) light. It is a natural part of daylight and, in itself, not harmful.

Studies have shown, however, that blue light emitted from electric devices impacts on our brain function, memory, attention spans and levels of alertness. Not all these things are bad. Smartphone screens and tablets are designed to help us focus and concentrate after all. Blue light’s effect on sleep is perhaps more controversial. Many medical professionals suggest avoiding it in the evenings altogether.

What Are The Different Sources of Blue Light?

Blue light is around us all the time. In its natural form, you can get exposed to it through sunshine. However, today you’re also regularly exposed to it through the many electronic devices and artificial light sources we enjoy at home.


Laptop screens


LCD monitors








LED televisions


LED bulbs


Fluorescent Lights

It is probably impossible to avoid blue light in 2022 so it is worth thinking about when and how you are exposed to it. Whatever the source, blue is not the best colour light for sleep.


Why Does Blue Light Affect Sleep?

Because of its wavelength and energy, our eyes are not brilliant at blocking or filtering blue light. Almost all of it passes straight through to the retina at the back of the eye.

Blue Light Affect Sleep

The retina is the screen that turns patterns into electrical impulses. This gives your brain more work to do converting the retina’s neurological responses into recognisable images. This amount of processing usually, thanks to our human circadian rhythms, happens in the daytime.

Circadian rhythms is the term used to describe our natural 24-hour body cycles. We go through physical, mental and behavioural changes each day. Scientists have found a small part of the brain, right in the centre, that controls them. It is, amongst many factors, influenced by light and darkness. This suited our ancestors, who couldn’t do much hunting and gathering when it was dark. Our bodies evolved to ‘switch off’ until the morning.

In today’s world, natural darkness presents no challenge at all. We have replaced it with electrical light and can work around the clock. Phones and screens keep you awake working against our circadian nature. Why is blue light bad? Why do doctors say to avoid blue light before bed? Its wavelength and energy levels keep your brain more active than other colours on the spectrum.

Protecting Yourself from Blue Light

There are a number of ways to counteract the problem of blue light affecting your sleep. The easiest is certainly to stop using devices at night. Many people say sleep improves after smartphones, tablets and e-readers are banned from bedrooms or shut off past a particular time. Giving your eyes, retina and brain a rest as part of the process of winding down at the end of the day will do you the world of good.

If you need to use devices into the night, then it is worth imposing a system of ‘eye breaks’ into your routine. A popular choice is often referred to as the 20-20-20 rule. Adopting this means shifting your gaze away from the blue light source every twenty minutes to an object 20 feet away for at least 20 seconds. You can also blink your eyes quickly 20 times after that to ensure your eyes get a refresh. There are plenty of other routines and practices to apply if simply turning off your light source isn’t an option.

There are also a number of computer glasses and screen filters available that filter blue light before reaching your eye. Some smartphones and tablets have specific night modes that ensures their screens emit less harmful colours.

Blue light needn’t ruin your sleep. With a bit of careful thought and effective management of electronic devices, you can ensure your eyes and brain better align with your circadian rhythms You’ll soon be getting exactly the levels of rest you need every night.


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