Light is essential to our daily lives and bodily functions. The sun is our natural source of blue light. Blue light from the sun help regulate our wake-and-sleep cycle, also known as our circadian rhythm. The sun also has other health benefits as it provides us with vitamin D and plays a role in a children’s eye development. However, artificial sources of light, including our smartphones, tablets, and computers have light-emitting screens with peak emission in the blue wavelengths of the light spectrum, which can interfere with our circadian rhythm. As we spend more and more time on digital devices, we aim to understand the impact this has, not just on our circadian rhythm, but also on our eyes and our visual system. The research will take time and there is still much we do not know regarding this digital light exposure. However, we can draw some conclusions from existing research on the subject. Let’s discuss what we know to be fact or fiction and shed some “light” on the blue light debate.
First, what is blue light?
When we talk about blue light, we are referring to a specific range of wavelengths in the visible light spectrum. Blue light is composed of short, high-energy waves. The high energy emitted from blue light is the main concern for its impact on our vision and eye health.
Blue light only comes from our cell phones and computer screens (Fiction)
The main source of natural blue light is the sun. Our digital devices emit some blue light as do fluorescent and LED lights in our home, offices, buildings.
Digital devices that emit blue light disrupt sleep patterns (Fact)
When the eye is exposed to blue light, the photoreceptors found in our retina send a signal to our brain to suppress melatonin and alter circadian rhythm. This keeps us alert, which is helpful during the daytime but can be disruptive to our sleep patterns when exposure occurs in the evening or nighttime. Limiting blue light from devices during these hours can have benefits to the length and quality of our sleep.
Blue light emitted from digital devices can damage our eyes (Fiction, for now)
While high amounts of blue light can harm the eye, in particular the retina, the amount of blue light emitted from smartphones and tablets is well below the safe viewing limits. Studies show that even during prolonged periods on digital screens, there is no harm to ocular structures. What we don’t know at this time, is how a lifetime of digital screen use will impact our eye health. This is an ongoing area of debate and more research is needed.
Blue-blocking lenses will help reduce eyestrain at the computer (Fact and Fiction?)
While research studies are divided on this claim, we as providers have seen our patients benefit from blue-blocking lenses in reporting more comfort while using digital devices. Whether this is a placebo effect or not is unclear, but more research is being conducted on this subject. Other factors that may be affecting our eyes on computer screens include blink rate and viewing distance. We blink less on the computer, which can contribute to dry eyes (having sandy feelings in your eyes, eyes feel tired, blurry vision).
Blue light influences mood and cognitive function (Fact)
Blue light does improve cognitive function by stimulating alertness, as discussed previously, with its effect on circadian rhythm. A study conducted in a classroom setting found that students taught and tested under blue-enriched light had faster cognitive processing speed and made less errors. Of note, this was light from an overhead light and not a digital device. Blue light has also been shown to improve mood.
Blue-blocking lenses block all the blue light getting into the eye (Fiction)
Blue-blocking lenses do not block 100% of blue light to the eye. Depending on the lens design between 10-30% of light is usually blocked either by reflecting the blue light or absorbing it. Blue light-reflecting lenses appear to have a blue-ish tint and block about 10% of blue light while blue light-absorbing lenses appear to have a yellow tint and block more blue light. A common lens we use in our practice is the Eyezen lens which blocks 20% of blue light. The more blue light a lens blocks, the more yellow or orange the lens will appear. It is a fine balance between the optics of the lens, the cosmetic appearance of the lens, and the blue-blocking effectiveness of the lens.
There is no doubt that blue-light-emitting devices will continue to be a constant in our modern world. As we’ve discussed, blue light is not inherently bad. It helps us maintain alertness, good cognitive function, and positive mood when its exposure occurs during the correct time of day. However, we must continue to strive to understand how our prolonged time spent on blue-light-emitting devices will impact our eyes and overall health. We do not yet know how a lifespan spent on digital screens will affect our retina and conditions like macular degeneration. While we may not have all the answers right now, we can confidently say that blue-light-blocking lenses are a good consideration to help regulate circadian rhythm, sleep schedule, and possibly digital eye strain.
By Dr. Laura Karle
References:
- Centers for Disease Control and Prevention. (2020, March 31). Module 2. the color of the light affects circadian rhythms. Centers for Disease Control and Prevention. https://www.cdc.gov/niosh/work-hour-training-for-nurses/longhours/mod2/20.html#:~:text=Exposing%20the%20eyes%20to%20blue,to%20yellow%20and%20orange%20light.
- O’Hagan JB, Khazova M, Price LL. Low-energy light bulbs, computers, tablets and the blue light hazard. Eye (Lond). 2016 Feb;30(2):230-3. doi: 10.1038/eye.2015.261. Epub 2016 Jan 15. PMID: 26768920; PMCID: PMC4763136.
- Ong, E. M. (2021, May 28). What are blue-light-blocking glasses and how do they work?. Rocket Eyewear Worldwide. https://rocketeyewear.com/blogs/news/what-are-blue-light-blocking-glasses-and-how-do-they-work#:~:text=Blue%2Dlight%2Dblocking%20filter%20technology,like%20a%20sepia%2Dtoned%20print.
- Wong NA, Bahmani H. A review of the current state of research on artificial blue light safety as it applies to digital devices. Heliyon. 2022 Aug 15;8(8):e10282. doi: 10.1016/j.heliyon.2022.e10282. PMID: 36042717; PMCID: PMC9420367.
