A common question I get from my patients is “should I be worried about blue light?” In recent years, with more adults and children spending more time on digital devices, people have started to wonder more about the harmful effects of blue light. Here are 5 essential things you need to know about blue light:
1. What is Blue Light?
It’s helpful to understand what exactly blue light is. Blue light, also called High Energy Visible (HEV) light, is one part of the light spectrum. There is actually a lot of different types of light which form the light spectrum (see diagram).
Most light cannot be seen. Non-visible light includes ultraviolet (UV) light, infrared, and X-rays. Of the light which humans can see, called visible light, there is a whole spectrum of light colors. This includes all the colors that create a rainbow – such as red, green, yellow, and blue.
People are exposed to blue light throughout the day from many sources including sunlight, fluorescent lighting, LED light bulbs, computer screens, and cell phones. Interestingly, sunlight is the greatest source of blue light exposure. Since people stare at smart phones and computers more and more these days, there is a lot of concern about what all that blue light exposure is doing to our eyes. Interestingly, in general, even if people spend hours on their digital devices, they still receive more blue light from simple exposure to sunlight.
2. How Does Blue Light Affect My Sleep?
Research has shown that exposure to blue light can affect how we sleep. Blue light stimulates retinal cells in the eye and decreases the amount of melatonin in our body. Melatonin is naturally produced in our body at night to help us feel sleepy. With less melatonin, one may have trouble sleeping. Studies have shown that blue light exposure can actually disrupt and change the body’s circadian rhythm, the natural wake and sleep cycle. It is generally agreed that screen time before bedtime can affect one’s ability to get a good night’s sleep.
3. What to Do at Night with Blue Light?
To sleep better, I recommend avoiding digital screens at least 2-3 hours before you go to bed. This advice may not be practical for most people. Another option - your smart phone or device may have a “night mode” feature which dims the screen and reduces the amount of blue light. You may consider using this feature on your device.
4. My eyes bother me after long screen time. What is that?
Eyes can feel fatigued and tired from using the computer or cell phone for long periods of time. Many people experience this often. This is something called digital eyestrain. In brief, digital eyestrain is fatigue and drying out of the eyes from not blinking enough. While this is a real problem that many people have, fortunately, it is not typically associated with any permanent damage. It also is not related to blue light.
5. Does Blue Light Damage the Eyes?
Fortunately, to date, there is no scientific evidence that blue light from digital screens directly damages the eyes. This includes blue light from all sources (such as digital screens and the sun). This is my opinion and also the opinion of The American Academy of Ophthalmology. That being said, research on blue light exposure is still ongoing. Until further studies are done, though, I tell my patients that they do not need to wear special blue light blocking glasses. This is good news – one less thing to worry about!