To begin, let us explain what blue light is. As you may know, visible light as we can see is made up of different colours, such as red, yellow, green, blue etc. Combined, these coloured lights make up sunlight, or white light. However, different light colours carry different amounts of energies, and have different wavelengths. Without getting too technical, with the rainbow as an example, the colour which carries the least energy would be the colour red. Following the order of the rainbow, Red<Orange<Yellow<Green<Blue<Indigo<Violet, is the order of ascending energy levels, and inversely, decreasing wavelengths.
Therefore blue light, which falls towards the most energy end of the spectrum, contains enough energy to harm your eyes. Past the visible light spectrum would be the ultraviolet range, as it contains more energy than violet.
So approximately one-third of all visible light is considered high-energy visible (HEV) or “blue” light. As with UV light, blue light has both benefits and dangers. Here are some things you should know about blue light:
1. There is blue light everywhere
Aside from sunlight, our main source of blue light, in this digital age, it is virtually inescapable. Every screen you can see emits man-made blue light, from computer displays to smartphones, LED lighting and even your kindle. Although the amount of HEV light these devices emit is much much lesser than that of the sun, but our prolong exposure and closeness to the screens may cause much concern for our eye health.
2. The reason for blue skies
Why is the sky blue? Well, to avoid an over scientific explanation, when blue light hits air or water molecules, it scatters much more easily than light rays of a different colour. Thus, this causes the sky to look blue.
3. Blue light passes freely through our eyes
Although our eyes are capable of preventing UV rays from reaching the retina at the back of the eyeball, with an efficiency rate of more than 99% of UV rays blocked, the same cannot be said for blue light. Blue light mostly passes unhindered by our cornea and lenses to hit the retina.
4. Macular degeneration may occur as a result of blue light
Macular degeneration occurs when there is damage to the macular of the retina, which will worsen vision and lead to an inability to recognise faces, to drive, read and perform other tasks. The fact that blue light passes unhindered into our retina causes it damage when there is an overexposure as the retina is extremely light sensitive, and can lead to permanent vision loss.
5. Digital eye strain is a result of too much blue light
When the eye receives too much blue light from digital devices, there is a chance of straining it, as blue light is not easily focused. Wearing yellow tinted computer glasses may soothe and protect your eyes. Thus, it would be good to invest in a pair of computer lenses, especially if you do a lot of work or play many games on the computer.
6. Some blue light may be good for you
However, as with many other things, blue light is only bad for you in copious amounts. In small amounts, however, blue light boosts alertness, helps memory and cognitive function and elevates mood.
Blue light has also been used as a treatment for certain forms of depression. A daily dose of blue light is also necessary to regulate your circadian rhythm and get your sleep cycle back in order, though an overexposure to it at night, such as reading on your kindle, may cause you to be unable to sleep at night.