What is Blue Light?

Light is made up of particles that travel in waves which emit energy. These particles range in length and strength for example the shorter the wavelength the higher the energy, and the longer the wavelength the lower the energy. Wavelengths of light are measured in nanometres (nm) and each wavelength range is a different colour as the graph shows.

Natural Blue Light

Blue light is found both naturally and artificially. When you go outside blue light is emitted from the sun. Blue light from the sun is essential in regulating your sleep and wake cycles and your body clock. Blue light has also been shown to improve alertness, reaction times and create a sense of wellness. Blue light from the sun is essential. Blue light from the sun is also accompanied by all the other colours from the light spectrum, making it a balanced and healthy light source. In winter months when the sun does not come out we can suffer from Season Affective Disorder (S.A.D) which lowers mood and heightens feelings of depression and anxiety.

Artificial Blue Light

Blue light is also found artificially from electronic devices which include your smart phone and computer screens, as well as from light bulbs.

The Dark Side of Blue light


We know that the shorter the wavelength of light the higher the amount of energy it contains. Blue light found at the very beginning of the visible light spectrum meaning it contains intense amounts of energy. Blue light ranges from 400-495nm. The light found in digital devices and light bulbs contains far more blue compared to other colours in the spectrum meaning our eyes are receiving too much unbalanced blue light. This blue light penetrates the eye and over the course of a day will cause digital eyestrain. Digital eyestrain is characterised by dry itchy eyes, headaches and fatigue. Digital eyestrain can also progress into macular degeneration over time. In winter, the sun does not come out as much as the summer months which leads us to use more artificial light sources. This contributes to S.A.D by keeping our cortisol levels (stress hormone) chronically high as excessive blue light raises your stress hormones. Coupled with lack of sunlight this can lead to stress, anxiety and depression.

A Case of the Blues…..and Greens


Our body clocks and sleep wake cycles are entrained by blue and green light. In the morning when we see blue light from the sun it tells our brain that its day time and to make us feel alert and awake. When the sun sets and it becomes dark the removal of blue and green light tells our brain its night-time. This sends a signal to the brain to secrete melatonin (sleep hormone) which then makes us feel sleepy and eventually sends us to sleep.

Green light that disrupts our sleep is found between 500-550nm and is just as influential at disrupting our sleep than blue light. In modern society, after dark, we now switch on our cell phones, watch TV or turn on our house lights which all contain blue light. This blue light sends a message to the brain telling us its day time, so we do not need to relax or feel sleepy. Exposure to blue and green light from digital devices, TVs and light bulbs after dark is disrupting our sleep. Harvard University has shown that exposure to blue and green light after dark disrupts our sleep and increases our risk of type-2 diabetes, depression, heart disease, anxiety and cancer.

Beating the Blues


To effectively combat the negative effects of artificial blue light during the day its essential to wear blue light filtering computer glasses. These glasses filter out harmful blue light from digital devices allowing you to beat digital eyestrain. To beat S.A.D along with depression and anxiety it is paramount to wear mood booster glasses that contain a light-yellow lens. This helps reduce the stress causing wavelengths of blue light whilst brightening up your view on the world. In order to get the best night’s sleep, it’s a must to block blue and green light after dark with red lens blueblocker glasses. This way melatonin can be produced effectively and diseases such as cancer, diabetes, heart disease and depression can be avoided.