Blue Light and Health (Plus: How to Make Your Own Blue-Blocking Glasses)
Note: This has been split into two updated articles on my personal website as I wanted to update and expand upon both areas, i.e., blue light and health, and blue blocker comparison and DIY. A lot of people have this Medium.com article bookmarked, but to get the most up-to-date versions of these articles, use these links:
Light is a ubiquitous health variable that few understand and many dismiss. Why does light deserve our attention? Consider this: every cell in your body is tied to CLOCK genes. The name fits these genes — they act like little cellular clocks, keeping track of the time of the day. Their primary environmental time cue is light.
Note: I couldn’t help digging into the science, so that’s first. But if you’re aware of the science already, you can jump to the section comparing blue blockers that also details how to make your own by hitting CTRL+F and typing “a survey of”.
Your body has trillions of cells, which means it has trillions of clocks. They communicate with one another to keep track of your circadian rhythm, which ultimately governs every aspect of your biology, from body temperature to hormone regulation to cell regeneration.
The master timekeeper of these trillions of clocks that keeps everything in sync is a mass of 20,000 nerve cells in the hypothalamus of your brain called the suprachiasmatic nucleus (SCN).
Given that coordination between cells (and, in turn, their clocks) is so crucial, it’s unsurprising how research continually turns up health problems tied to disorders in circadian rhythm. Did you know that
- Proper sleep suppresses inflammation via the BMAL1 CLOCK gene?
- When CLOCK genes like PER2 and BMAL1 get uncoupled, lung tumor formation is more likely?
- If CLOCK genes like BMAL1 and REV-ERBα don’t function correctly, cells can’t rest, which allows cancer to replicate more quickly?
- Artificial blue light — regardless of time of day — alters glucose metabolism (blood sugar) and sleep cycles?
There is a specific field in medicine — called chronopharmacology — that the looks at the interactions between drugs and CLOCK genes. Timing matters when introducing agents into biological systems. For example, did you know that whether a mouse administered e. coli lives or dies depends on the time of day of the injection?
The simplest analogy to your body’s circadian rhythm is a symphony. The orchestra are your trillions of cells. The conductor is the SCN. When everything sync ups, you get a beautiful song — the composer’s intent. When people start playing in different times, out of tune, etc., you lose the song entirely.
With an actual symphony, the toll paid for an “off” performance is a bad song. When it comes to biology, the penalty is poor health and disease states — whether it be cancer, more inflammation and/or altered blood glucose levels — as some of the research bullet points above show.
If you’re a biology research geek and the cites above have piqued your interest, be sure to check out my public Dropbox folders. Instead of abstracts, I have full-text versions of papers cited above, as well as hundreds more.
Understanding Sleep/Wake Cycles
Much of the research on circadian rhythm focuses on melatonin, a hormone produced in your pineal gland that helps regulate your sleep, causing drowsiness at appropriate times. It should be noted that while melatonin has been called “the chemical expression of darkness” and makes sure you enter proper sleep cycles at night, it relies on light/dark cues processed by your SCN.
If melatonin (via the SCN) helps regulate sleep, what helps with wakefulness? That’s the role of cortisol. There’s such a surge of it first thing in the morning that that we have the term cortisol awakening response. After this surge, it slowly drops and levels off throughout the day.
In a normal person under close-to-natural conditions, you get a these two bell curves you see below, with cortisol peaking in the morning and lowering toward evening, and melatonin peaking in the evening and lowering throughout the day.
How does the melatonin portion of the above chart play out at the CLOCK level? Foster and Kreitzman note in their book, Seasons of Life:
There is a very high density of melatonin receptors in the individual cells of the pars tuberalis (PT). Melatonin binds to these receptors, which alters the gene expression of several of the clock genes, including the Per and Cry genes … within the cells. … Cry gene expression tracks melatonin rise (dusk), whereas Per gene expression tracks melatonin decline (dawn). [Pages 81–82]
Light: Then and Now
Notice how above the melatonin and cortisol chart, I used the words “close-to-natural conditions.” That was intentional. Up until Edison patented and commercialized the light bulb in the 1880s, we, as a species, were used to light from the sun during the day and darkness at night, or minimal, man-made light sources like candlelight and gas lamps at night, thus living under close-to-natural conditions dictated by the rising and setting of the sun.
The above picture from space shows our current nighttime reality. 54 percent of the world’s population lives in urban areas — the major source of this severe light pollution — and that number is expected to grow to 66 percent by 2050.
Research has found that 80 percent of the world’s population lives under light-polluted skies. If you narrow this down to just the United States and Europe, the number climbs to 99 percent. The virgin night sky is now so foreign to the majority of individuals that it requires going to a very remote area or a major event like a blackout to experience the night sky as intended.
The light landscape changed drastically in a very short period of time. Instead of sunlight during the day and darkness at night, most of us are bathed in artificial light almost 24/7.
What colors are now most prevalent? If you compare the visible spectrum reference chart below to common artificial light sources above, you’ll notice we’re getting a unbalanced surplus of violet, blue, and to a lesser extent, green.
Popular devices like iPads and iPhones feature these same peaks in the violet (380–450 nm) and blue range (450–495 nm) that we see from other artificial light sources.
Melatonin: The Chemical Expression of Darkness
90 percent of Americans use light-emitting electronics within one hour of bedtime. Exposure to violet, blue and even green light (495–570 nm) after sunset has two primary effects: melatonin suppression and phase shifting or re-tuning.
Let’s cover melatonin first. As noted in the section above, melatonin helps regulate sleep. It should be obvious, but it must be stressed: we are meant to have complete darkness at night. Cell phones, tablets, TVs, overhead lights, lamps, LEDs, etc., are not natural.
This is why studies continually find that violet and blue light suppress melatonin production the most. For example, something as seemingly innocent as room light can reduce pre-sleep melatonin levels by 71.4 percent and daily melatonin levels by 12.5 percent. This suppression effect is much greater in children than adults.
As you move further away from violet and blue (380–495 nm) toward green (495–570 nm), yellow (570–590 nm) and orange (590–620 nm) spectrum, the melatonin-suppressing effects aren’t nearly as great. Green light is about one quarter to one half as potent as blue, and yellow, orange and red have next-to-no effects on melatonin.
If you’ve been clicking on the research links, you’ll notice several mention the term “lux.” This is shorthand for saying the total amount of visible light present and its intensity on a surface. The higher the lux, the more intense the light source.
Complete darkness would be zero lux. As you can see above, something like a night without a full moon is only 0.002 lux. Compared to a moonless night, a typical living room light is 2,499,900 percent more intense. No, that number was not a typo.
Combine intensity (lux) with these violet, blue and green ranges (380–570 nm) and you’ve got a potent cocktail. Higher lux values amplify the damaging effects of these nanometer ranges. That’s why — if you go back to the previously cited study — you see a 301 percent increase in melatonin suppression between the 15 lux and 500 lux control groups.
When melatonin levels are disturbed and start to drop, the sleep/wake cycle is thrown into disarray and your body can’t properly utilize autophagy —an essential cellular maintenance and cleanup process. Melatonin is critical not only for this sleep/wake cycle, but the hormone itself
- Is a more effective antioxidant than vitamin E
- Reduces oxidative stress
- Makes mitochondria (your cell’s power plants) more efficient
Given the melatonin-suppressing effects of violet and blue light, it should be self evident that if you block that range of light (380–495 nm) from hitting your eyes, you help preserve melatonin levels and thus keep sleep/wake cycles in order.
And that’s exactly what the research finds. Keep in mind: most of these studies only look at glasses that block violet and blue (and some green). We would expect glasses that additionally block all green to have even more benefits.
Excuse Me: What Time Do You Have?
When your circadian rhythm is running correctly, you can say you have a normal phase response curve. However, as you learned in the previous section on melatonin, violet, blue and green light start to shift sleep/wake cycles.
Organisms are so sensitive to light that just a single pulse of the wrong kind of light can initiate a process called phase shifting or re-tuning. Like with melatonin suppression, the greater the lux, nanometer range and length of exposure, the greater the phase shift.
You may be thinking, “Well, I bet it takes days, weeks, months, heck, even years, before you start to see changes at the genetic level from artificial light and phase shifting.”
Sorry to burst your bubble. As noted in the introductory section, every cell is connected to time and the greatest environmental time cue is light. We’re so wired to pick up light, that we can detect a single photon. And all it takes is one night of artificial light throwing off your sleep to alter CLOCK genes and, in turn, affect gene expression.
How do we combat this phase shifting? Per the melatonin section, any kind of barrier — like blue-blocking glasses — that stops 380–570 nm of light will help preserve melatonin and help normalize circadian rhythm. If trying to keep things dark (or as close to dark as possible) during the night helps, then the corollary should be true, i.e., sunlight during the day should help, too.
That’s exactly what Environmental Health Perspectives published:
When people are exposed to sunlight or very bright artificial light in the morning, their nocturnal melatonin production occurs sooner, and they enter into sleep more easily at night.
This should not be misinterpreted to say, “Any light is good during day.” It depends on the type of light. The above quote notes the importance of sunlight, which has a balanced spectrum. (Remember the chart from earlier?) Humans have lived under the sun’s influence for 200,000 years.
Indeed, research shows that when groups are exposed to daytime artificial light sources that are warmer and more balanced (less blue) and light sources that emphasize primarily blue, the warmer light group has circadian rhythms that more closely match the rising and setting of the sun whereas the blue light group gets entrained to unnatural rhythms:
The results confirm that light is the dominant zeitgeber [environmental cue] for the human clock and that its efficacy depends on spectral composition. The results also indicate that blue-enriched artificial light is a potent zeitgeber that has to be used with diligence.
The Eyes Have It
One last biological stop before we nerd out on blue-blocker glasses: your eyes. First and foremost, you have to understand how you see the world.
Visual perception occurs when light in the 380–780 nm range hits the retina. Ultraviolet and infrared wavelengths aren’t absorbed the retina, but by the outer layers of your eyes — the cornea and lens.
Within the retina is a light-sensitive protein called opsin. When photons hit the retina, opsin combines with other molecules to start a series of photochemical reactions, which create retinal molecules that are either stored in an area called the retinal pigment epithelium (RPE) or combined with opsin again to complete the visual cycle.
That area just mentioned — the retinal pigment epithelium (RPE) — is very important to our discussion moving forward. While RPE cells aren’t photoreceptive, they make sure visual pigments can regenerate and that photoreceptors survive and function normally by providing nutrients and oxygen, as well as help remove oxidized (problematic) cells.
While RPE cells don’t initiate the reactions that make the visual process happen, they do protect molecules that allow it to happen. That’s why once RPE cells start to take on too much damage, you get diseases like macular degeneration, and if enough cumulative damage occurs, blindness.
Some portion of blue light is vital to life. If it wasn’t, it wouldn’t be part of the sun’s spectrum. In fact, a photopigment called melanopsin targets the SCN to set the circadian clock. Research indicates melanopsin is most sensitive to 480 nm, which is near the end of the blue light spectrum.
How much blue (in particular, 480 nm) do we need during the day to set our clocks? More research needs to be done, but it appears as little as 30 minutes of sunlight helps with sleep quality and hormone responses, as well circadian timing.
Remember how in the section on phase shifting, we went over that not all light during the day is beneficial and that it’s better to get sunlight or try to mimic the sun rather than use blue-enriched light? The same holds true for eye health — in particular, RPE cells — regardless of time of day.
The above chart is extremely important. It shows that at all times violet and the beginning of the blue spectrum have an extremely phototoxic effect, i.e., exposure to light in that range is particularly effective at killing RPE cells.
Knowledge of this light range on retinal damage goes back to 1966. In fact, this problem is so well known in many research circles that it’s called the blue light hazard. Recent research has highlighted this same problem area, noting:
An emission peak of around 470–480 nm should be preferred to … an emission peak below 450 nm.
The obvious connection to too much damage to RPE cells we covered earlier, and that is macular degeneration. There is also one other, very significant area impacted by violet and blue light destruction of RPE cells: docosahexaenoic acid (DHA), more commonly known as the most effective portion of fish oil.
Photoreceptor cells in the retina have the highest DHA content of any cell type. And since RPE cells protect photoreceptors and actively consume DHA, it’s easy to see that if destroy RPE cells, you destroy some of your body’s greatest DHA stores.
But why should we care about DHA? Not only might DHA be necessary to completing the visual cycle, i.e., allowing you to see, but research continually finds that DHA “may indeed have a special place in biological systems.”
What makes DHA have a special place? It has been “the dominant fatty acid … for all 600 million years of animal evolution.” In fact, if we don’t get enough fatty acids, a syndrome called essential fatty acid (EFA) deficiency kicks in.
While there are many essential fatty acids, guess which one alone can completely obliterate EFA deficiency? That’s right: DHA. Not only can DHA help lower blood pressure, but it can increase the release of adenosine triphosphate (ATP), which allows more chemical energy to be made available for all cells.
Given DHA’s critical place in our biology, it makes sense the upping levels helps with conditions like high blood pressure. As noted earlier, the retina has the highest concentration of DHA. Therefore, we would assume that if we keep DHA levels topped off, we would should be able to better prevent RPE-damage-linked conditions like macular degeneration, and that’s exactly what the research shows.
The DHA-retina link to circadian rhythm can be found in proteins like rhodopsin, which convert light to electrical signals in the retina, that in turn talk to the SCN. DHA enhances and protects rhodopsin whereas blue light:
Bleaches the vast majority of rhodopsin, especially at night, [and] can overwhelm the photoreceptor’s capacity to prevent damage.
Before moving on, it should be noted that DHA found in seafood is superior to fish oil capsules because it is not only less prone to oxidation (it’s more stable), but is better absorbed in your intestine (it’s more bioavailable) and more easily reaches your brain.
Now, it’s finally time: let’s get into the blue blockers currently available and learn how to make your own.
A Survey of the Blue-Blocker Landscape
Given the bevy of research showing the harmful effects of artificial light — in particular, violet and blue — it makes sense the companies and entrepreneurs have populated the market with blue-blocking glasses.
The table below is by no means an all-encompassing list, but it does represent some of the more popular blue-blocking options available. You’ll note that the BPI options are tints only. I included them as they’re part of the how-to portion of this article.
You could divide this table into two types of blue blockers, i.e., daytime glasses (such as BluTech and Gunnar Optiks) that block portions of the violet and blue light spectrum vs. nighttime glasses (such as Uvex and BPI Monochrome) that block all of the violet and blue spectrum, and either none, some or all portions of the green, yellow and orange spectrum.
Per the introductory science section above, it’s worthwhile to block artificial violet and blue light at all times. Bare minimum, you should block the 380–450 nm range (violet) during the day and the 380–495 nm range (violet and blue) during the night. If you want maximum melatonin production at night, take it a step further and block green (495–570 nm), too.
Why Make Your Own Blue Blockers?
Above, we covered many ready-to-buy options. However, they suffer from problems, such as
- Many don’t allow you to use your glasses prescription, so you either have to lay glasses on top or under these kinds of blue blockers.
- Some manufacturers don’t publish their spectrum chart, leaving you to rely on online reviews and test yourself.
- They don’t allow you to customize your frames style, leaving you stuck with whatever design the manufacturer provides.
- They don’t account for use case, i.e., you might want a custom tint for a particular situation or time of day.
- Cost. You can easily spend $200+ on a single pair of Crizal Prevencias that don’t block 100% violet or blue light, or you can spend less than $150 to buy all the equipment below to make multiple pairs of more effective blue blockers for yourself, friends and family members.
What You Need
Cost will vary depending on what supplies you have and what grade of equipment you buy. You can calculate based on the prices I list below.
- Electric burner ($9.99 and up)
- Glasses with CR-39 plastic lenses with no-to-minimal coatings, e.g., UV blocking and nothing else ($6.95 and up at Zenni Optical)
- Lens holder ($24.68)
- Empty container, e.g., paint can ($5.60 and up)
- Gram analog or digital scale ($9.99 and up)
- Preferred BPI tint(s) ($29.95/tint and up)
- A stirrer (a spoon or kebab stick will do)
- A small bowl filled with cool tap water
- Two tissues
- Analog or infrared thermometer ($5.60 and up)
Getting the Lenses Ready
The first thing we have to do is get those lenses out of the frames. I like working with full-rim frames as it makes this easy. All you have to do is apply some pressure with your thumb and the lens will pop out. You have to use a little force but don’t worry — CR-39 is very tough plastic. Let’s start with the right lens.
Before repeating this process with the left lens, make sure you are aware of where you’re setting the right lens as you don’t want to get the two lens mixed up if each has its own sphere, cylinder and axis values.
Now pop the left lens out.
If you’re working with lenses with different values, place something like a piece of tape on the right side of the lens holder to indicate the right lens. After that, place the lenses in the lens holder and push down to clamp them into place. Tip the lens holder to the side to make sure they’re snug and won’t fall out.
Prepping the Tint Solution
We need to figure out how much tint to use. Place your empty container (in my case, a paint can) on your scale and drop the lens holder into the container. Make a visual note of how far from the base of the container you have to go vertically until you reach the top of your lenses.
Once you’ve done that, take the lens holder out of the container and fill the container with tap water so that it goes about 25% higher than your visual note. Will the water is pouring, make a final note of the weight (I used 400 grams).
Once you have your water in the container and made a note of the weight, it’s time to add the tinting solution. We want to dilute the tint by 10, to give a 10:1 water-to-tint ratio. Since I had 400 grams of water, I poured in 40 grams of tinting solution. After you pour the tint, give it a stir so the water and tint are mixed together.
Lens ready. Tint solution ready. Time to turn up the heat. Make sure you do the do the next part in a well-ventilated area or outside.
Place your container of tinting solution on your electric burner. Crank the heat to max. Step away a couple of minutes and come back. Check the solution temperature with a thermometer. Once you get to 175°F or more, lower the burner heat to medium-high (4 to 3 on my burner).
Give the solution a stir and submerge your lens holder. Start your timer and set it for the appropriate time per the instructions on the tint bottle (45 minutes is needed for UV-Blue 450/Winter Sun). While the lenses are cooking, fill a bowl or container with cool tap water (it needs to be deep enough to completely submerge the lenses).
While BPI claims you need to stir the solution often, you really don’t. Unless you get a rolling boil, you can simply stir it once or twice.
Be sure to check how your lens are doing every 10 minutes or so. If you notice that your lenses are starting to get exposed because too much of the solution has evaporated, pour in some more water and a tiny amount of tint and give it a stir. It’s OK to eyeball this. If you end up doing this, add an additional minute or two to your cook time to compensate for the dip in what was a consistent temperature.
Note: This is why I said at the beginning to pour more water than you think you’ll need as it evaporates during the cooking process. However, I wanted to have the tip above in case you come out to check on your lenses and go, “What do I do?”
Cooling, Cleaning and Assembling
Almost done. Once you’re timer rings, turn off the burner, take the lens holder out of the container and immediately submerge the lens holder in your bowl or container of cool water.
How long do the lenses need to completely cool and finish setting the tint? Honestly, I’m not sure. My guess is probably only five minutes, but it’s better to err on the side of caution and let them sit in the cool water for 30 minutes.
Once the lenses are cool, take them out of the solution. You may notice a blotchy, non-consistent look before cleaning with deeper tints like Diamond Dye 500/550— that’s normal. Dry and clean them by rubbing them with a tissue, making sure to keep track of which is the left and which is the right.
Last steps. Push the appropriate lens into the correct side of the frame. You’ll have to use even more force than you did to pop them out. Once the lenses are snug in the frames, you’re done!
Frequently Asked Questions
Q: How did you come up with this tinting process?
A: A Facebook friend, JJ Yeo, tested out the BPI Diamond Dye 500/550 tint and shared his results with me and others. I tweaked his process and used different supplies. I tested this out on three sets of glasses with three tints to make sure it could be duplicated consistently before writing this article.
Q: I got my box of supplies from BPI. I noticed they call for a lot more steps and supplies. Did you leave out steps?
A: Yes, my instructions do not match BPI’s 100%. BPI normally sells to opticians that tint large quantities of glasses in big vats. You’ll only be making a pair of glasses or two at a time, so my guide will work for you. My guess is BPI wants to sell additional products. There’s no need to use their lens prep product as having new, clean, plastic lenses means they’re already “prepped.” BPI does not talk about diluting their dyes, but I’ve tested out three pairs of glasses and can assure you, a 10:1 water-to-tint ratio is fine. If you didn’t do that, you’d be going through a bottle of tint per pair of glasses.
Q: Do I have to use CR-39 plastic lenses? Can I use polycarbonate lenses?
A: You don’t have to use CR-39 plastic lenses, but they’re the cheapest and absorb tints most effectively. I’ve never tested polycarbonate lenses, but have been told by opticians that they don’t absorb tints very effectively (plus, they will cost more than CR-39s). Rule of thumb: Get the cheapest plastic lens you can.
Q: Do lens coatings really matter?
A: Yes. The more coatings you put on a lens, the less tint the lens will absorb. Most companies (like Zenni Optical) put a UV-blocking coating on all lenses by default. That’s OK. All three pairs I’ve made have had that and it didn’t throw off the tinting process.
11.21.16 reader update: Someone tried to make a pair of BPI-tinted glasses using lenses with anti-reflective (AR) coating. Due to the coating, the BPI tint did not adhere. So, it bears repeating: get no additional coatings on your lenses. The only coating that does not mess up the tinting process is the default UV-blocking coating that most manufacturers use by default.
Q: I have plenty of tinting solution left in the can. Do I have to clean it out right away or can I reuse it?
A: Yes, you can reuse it. This makes total sense if you’re using the same tint over and over again on different pairs of glasses. I’ve left the tinting solution in the can for several weeks, reheated it and made another set of glasses in the same tint. Just make sure you have enough solution to submerge the lenses completely and account for what will evaporate during the cooking process.
Q: What are the best daytime blue blockers?
A: On a budget and don’t need prescription lenses? Then go with Uvex S1933Xs. They’re under $10. If you need prescription lenses, I’d honestly just bypass brands like Crizal Prevencia and BluTech, as you can buy prescription lenses and frames from somewhere like Zenni Optical and do your own custom tint like Winter Sun/UV-Blue 450 or Diamond Dye 500 for less money.
Q: What are the best nighttime blue blockers?
A: The best value pair (if you don’t need prescription lenses) are the DEWALT DW0714. They’re under $10 and block 380–565 nm, which is all violet, blue and almost all green. If don’t mind the cost ($129), Carbonshades are great as they block all violet, blue and green, but they don’t accept a prescription. If you need to support prescription lenses and/or want more control over your tint, I would use either BPI Diamond Dye 550 or Monochrome.
Q: If a tint or lens only absorb a certain percent of, say, the blue spectrum, is that still affecting my circadian rhythm and RPE cells?
A: Yes. Unless something is blocking 100% of a particular nanometer (nm) range, light from that spectrum is still hitting your retina, so it will have an effect. Now, the effect will be lessened if only 30% is getting through versus, say, 100%, but there will still be an effect, whether it be phase shifting/re-tuning and/or destruction of RPE cells.
Q: What is your personal protocol for blocking blue light?
A: I use this red tinting trick on my iPhone to eliminate both blue and green light at all times. I also have a Low Blue Lights filter on the phone for the times I need to let some green light out to see particular text.
During the workday I only use a single lamp in my office (no overhead fluorescent lights), use f.lux on my computer (always on the night/1200K setting) and wear glasses with the Winter Sun/UV-Blue 450 tint (I used to use BluTechs but found they let in too much RPE-damaging violet and blue light). I make sure to get outside in the sun as often as I can and take off my glasses so natural, full-spectrum sunlight is hitting my retina.
At night, I use amber, red bulbs and/or candles in my house. If I’m out with friends after dark or exposed to artificial light, I wear either DEWALT DW0714s or glasses with the BPI Diamond Dye 550 tint. I will probably make a pair of BPI Monochromes in the near future.
It boils down to this: I follow natural light and dark cycles. That means maximizing natural sunlight exposure during the day (as best I can given I have an office job) while minimizing violet and blue light exposure, and keeping things as dark as I can at night, letting only the yellow, orange and/or red spectrum in if I have light sources.
Q: You mentioned that the retina has the highest concentration of DHA and talked about how important DHA is. Does that mean I can simply take a lot of fish oil pills and not worry too much about blocking violet and blue light?
A: Remember from earlier: DHA delivered via seafood is much more bioavailable than pills. And if you block violet and blue light from damaging your retina, it’s preserved in your body and you don’t need to continually top it off. What’s more work for your body? Preserving what it does have and not bombarding it with damage or letting them damage take place and then trying to fix it? The answer should be self evident.