Blue light: it’s both good and bad for you

Although it is environmentally friendly, blue light can affect your sleep and potentially cause disease. Until the advent of artificial lighting, the sun was the major source of lighting, and people spent their evenings in (relative) darkness. Now, in much of the world, evenings are illuminated, and we take our easy access to all those lumens pretty much for granted.
But we may be paying a price for basking in all that light. At night, light throws the body's biological clock—the circadian rhythm—out of whack. Sleep suffers. Worse, research shows that it may contribute to the causation of cancer, diabetes, heart disease, and obesity.

So what is it?

Light is made up of electromagnetic particles that travel in waves.  These waves emit energy, and range in length and strength. The shorter the wavelength; the higher the energy. However the human eye is sensitive to only one part of this spectrum: visible light. Visible light is that part of the electromagnetic spectrum that is seen as colors: violet, indigo, blue, green, yellow, orange and red.  Blue light has a very short wavelength, and so produces a higher amount of energy. Studies suggest that, over time, exposure to the blue end of the light spectrum could cause serious long-term damage to your eyes. Blue light is everywhere in our world. It used to be that the only source of blue light was from the sun. Now we have brought blue light inside by way of digital screens (found on TVs, Smartphones, computers, laptops, tablets and gaming systems), electronic devices, LED and fluorescent lighting.Some studies suggest that not enough exposure to sunlight in children could affect the growth and development of their vision.
As one of the shortest, yet highest energy wavelengths in the light spectrum, the blue light flickers easier and longer than other types of weaker wavelengths. This flickering casts a glare that reduces your visual contrast, affecting clarity and sharpness. This can cause eye strain, physical and mental fatigue and headaches if you use your electronic devices or sit in front of a computer all day.
Our eyes have not evolved to provide filters against this type of artificial light. Prolonged exposure to blue light may lead to macular cellular damage, which may lead to loss of vision.

The medical profession is concerned exposure level of blue light for adults and children. Here are some interesting statistics:
  • 43% of adults have a job that requires prolonged use of a tablet or computer
  • 74% of teens between the ages of 12 to 17 use electronic devices at least occasionally
  • 70% of adults that regularly use electronic devices report symptoms of digital eye strain
  • 93% of teens have access to or have a computer.

Blue light Vs Sun light:

First, we need to understand where the sources of blue light come from. As mentioned above, sunlight has a combination of lights.
Sunlight is made up of red, orange, yellow, green, blue, indigo and violet light. When combined, it becomes the white light we see. Each of these has a different energy and wavelength. Rays on the red end have longer wavelengths and less energy. On the other end, blue rays have shorter wavelengths and more energy. Light that looks white can have a large blue component, which can expose the eye to a higher amount of wavelength from the blue end of the spectrum. Blue light isn’t some special form of light that only comes from computers and LED lights - it’s actually all around us. In fact, sunlight is the mai source of blue light. When you walk outside during the daytime, you’re exposed to blue light.

The blue light emitted by the sun is the reason we see the sky as blue. It's these light waves that get reflected and bounced around the most by the Earth’s atmosphere.

Electronic Devices

In today’s world, there are an increasing amount of artificial sources of blue light and we interact with many of them on a daily basis. Think digital display screens on laptops, tablets and smartphones.
The fact we spend most of our waking lives using screens - and at such close proximity - has eye doctors and other medical professionals concerned about the effects.Today, manufacturers use brighter LED lights because they are more efficient. LED screens are also thinner, lighter, and longer-lasting and have a better color resolution. But, it’s these brighter LED lights - along with modern day habits - that expose us to more blue light than ever before.Although the use of any form of the blue light filter may be helpful, one sure way to reduce digital eye strain and improve the quality of sleep is to avoid using the computer, smartphone, tablet, or TV for 30 to 60 minutes before bed.

May Cause:

Eye Strain
When all the colors are combined they create white light we all see from computers and more. However, did you know that each of those individual lights has both different wavelengths as well as energy? It’s true. While rays from red are longer wavelengths and have less energy, blue rays are shorter wavelength and have more energy. Because of those shorter wavelengths and higher energy, the blue light can cause a lot of strain on eyes, especially children’s. As a result, it’s important to take preventative measures as well as understand more about blue light. The best way to protect your eyes against eye strain from blue light in devices is to take regular breaks using the "20-20-20" rule: Every 20 minutes, shift your eyes to look at an object at least 20 feet away for at least 20 seconds.
If you have cataracts and are about to have cataract surgery, ask your surgeon what type of intraocular lens (IOL) will be used to replace your cloudy natural lens, and how much blue light protection the IOL provides. After cataract surgery you might benefit from eyeglasses that have lenses with a special blue light filter — especially if you spend long hours in front of a computer screen or using other digital devices.
 Retinal Damage:
Excessive exposure to blue light isn't great for our eyes, contributing to a slow loss of vision over the course of a lifetime.There are two types of 'photoreceptor' cells in the retina responsible for detecting light: rods and cones. Scientists from the University of Toledo in the US now understand precisely how this toxic effect works, which could be good news for anybody at risk of degenerative eye conditions. Increasing evidence suggests that blue light has a dark side. At night, it can suppress the secretion of melatonin and wreak havoc on our circadian rhythms, and recent studies have shown that extended exposure to blue light can damage the retina, though exactly how it does this has not been clear.
Age Related Macular Degeneration:
Age-related Macular Degeneration (AMD) is the most common cause of blindness in the elderly population in developed countries and accounts for 8.7% of all the blindness worldwide. In the future, the prevalence of AMD is likely to increase as a consequence of exponential population aging. The early stages of AMD, compared to its later stages, affect a significantly larger proportion of the population and increase the risk for visually significant advanced AMD by 12- to 20-fold over 10 years. Age related macular degeneration involves the slow breakdown of cells that sit behind the light-sensitive tissue on the inside of the eyeball, preventing the transfer of nutrients and removal of waste. There have been significant advances in the management of neovascular AMD and the introduction of anti-angiogenesis therapy can now prevent blindness and in many cases restore vision. However, the treatment modalities are expensive and not available to patients in many countries.The study provides a potential mechanism for the proposed link between blue light exposure and macular degeneration.