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. The length of the waves is measured in nanometers (nm), with 1 nanometer equaling 1 billionth of a meter. Every wavelength is represented by a different colour, and is grouped into the following categories: gamma rays, x-rays, ultraviolet (UV) rays, visible light, infrared light, and radio waves. Together these wavelengths make up the electromagnetic spectrum.
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 colours: 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 has a wavelength of between approximately 380nm and 500nm; making it one of the shortest, highest-energy wavelengths.
Sources of blue light include the sun, digital screens (TVs, computers, laptops, smart phones and tablets), electronic devices, and fluorescent and LED lighting.
The evolution in digital screen technology has advanced dramatically over the years, and many of today's electronic devices use LED back-light technology to help enhance screen brightness and clarity. These LEDs emit very strong blue light waves. Cell phones, computers, tablets and flat-screen televisions are just among a few of the devices that use this technology. Because of their wide-spread use and increasing popularity, we are gradually being exposed to more and more sources of blue light and for longer periods of time.
Blue light can help elevate your mood and boost awareness, but chronic exposure to blue light at night can lower the production of melatonin, the hormone that regulates sleep, and disrupt your circadian rhythm.
Harvard researchers have linked working the night shift and exposure to blue light at night to several types of cancer (breast, prostate) diabetes, heart disease, obesity and an increased risk for depression.
Researchers aren't exactly sure why exposure to blue light at night seems to have such detrimental effects on our health, but it is known that exposure to light suppresses the secretion of melatonin and lower melatonin levels might explain the association with these types of health problems.
Optometrists are even seeing high levels of retinal stress in young people that could lead to the early onset of macular degeneration, which in extreme cases can cause near blindness.
Most of us spend the majority of our waking hours staring at digital screen, whether it's the computer at work, our personal cell phone, playing a video game, or just relaxing and watching TV. Digital eyestrain is a new term used to describe the conditions resulting from the use of today's popular electronic gadgets. Everyone needs to take precautions against the effects of blue light. Whether we work in an office or play in the sun; spend hours staring at a computer screen or texting on our cell phones, we are all being exposed to blue light.
You can choose anti-blue light screen protector (yellowish/Lt. orange) which is effective in reducing blue light that from smart phone, tablet pc, LED screens. Taiwan Ophthalmologists Ye Wei Yi (葉威毅) said: "Regarding the impact of the spectrum, colors like yellow, orange, light orange, are better to cut off blue light, and image contrast can be increased at the same time." However, the most important thing is to take 10 minutes break while staring 30 minutes on screens.