Light is complicated. From bright sunlight on a summer day to the constant glow of our computers, we could not live without the many benefits of light. However, it can have its downside as well, such as something called blue light.

To understand why light can be detrimental, we need to start with some basics. To keep it simple, imagine that you could see the breakdown of light. While it appears clear to us, it’s actually made up of a spectrum of wavelengths associated with different colours and there is an inverse relationship between the wavelengths and the amount of energy they contain. 

At one end of the spectrum are the red and orange lights with longer wavelengths and less energy. At the other end, with stronger energy and the shorter wavelength, is invisible ultraviolet light. In the middle, bridging visible light and invisible light, are the blue lights. Combining increased energy and visibility, these blue lights are thought to be more likely to impact our eyes.

What does blue light do to your eyes? To start with the positive, it can help maintain a regular sleeping and waking cycle while also regulating mood. On the other hand, however, too much exposure is thought to contribute to digital eye strain.

To understand the complexity of blue light, here are seven facts outlining its benefits and detriments:

1. Blue light makes the sky blue

If you’ve ever had a child ask you why the sky is blue, here’s your answer. When high-energy visible light (HEV light) encounters atmospheric water and air particles it scatters more easily than any other visible light, thus making the sky appear that gorgeous shade of robin’s egg blue.

2. Blue light is also indoors

Although sunlight remains the primary source of blue light, we spend a lot more time in front of digital devices and computer monitors these days and this is a significant source of blue light. Our increasing use of screens has optometrists worried about the long-term impacts on ocular health.

3. Blue light can reach deep in the eye

The human eye is amazing. Even without sunglasses, our eyes will block 99 percent of UV light from reaching the retina. Sunglasses will assist with eliminating that final percent of invisible, high energy damaging light which can cause snow blindness and other eye problems. Blue light, however, is visible and will, therefore, pass unhindered through the cornea and lens and into the retina - that’s how you can see the blue colour.

4. Too much blue light may contribute to digital eye strain

We’ve already learned that high-energy visible light scatters easily. What this means when you’re staring at a computer screen is that your eyes are actually perceiving a whole bunch of unfocused visual noise which is thought to contribute to digital eye strain. In fact, 65 percent of American adults recently affirmed their eye strain symptoms in a survey by The Vision Council.

5. You can protect your eyes from blue light

It is possible to protect your eyes from too much damaging exposure to screen use. For one, you can purchase yellow-tinted glasses that block some wavelengths of visible blue light emanating from digital devices. Blue light filters can also be installed on computers, smartphones and tablets. An easy, inexpensive fix is to take breaks. Every few minutes look away from your computer screen or avoid screens altogether when you stop for lunch or otherwise take a break.

6. Blue light helps with seasonal depressive mood

Despite all these risks, it has also been shown that blue light can help improve mood. Therapies using blue light emitting lamps have been designed to treat seasonal affective disorder (SAD), a mood disorder related to diminishing light during the seasonal shift into winter. 

7. Blue light regulates our sleeping cycles 

Our bodies have natural cycles of sleeping and being awake and it’s blue light that helps to regulate these. During the day, exposure to blue light helps our bodies operate naturally. Too much exposure to it in the evening - by using smartphones in bed, for example - can disrupt these natural cycles by tricking the body into thinking it’s still day. Apps that block blue light can be helpful but better yet, head to bed with an old-fashioned book, rather than anything with a screen, in order to improve your sleep.

Enabling us to see, waking us up in the daytime, and helping with seasonal sadness are all benefits of blue light even while it can cause eye strain and potentially serious problems. As with anything, moderate your exposure to blue light and you’ll be sure to save your vision long into your old age. 

For more information on Blue Light, and to see how exposed your are - head over to