Blue (Gas?) Lighting

In 2024, the U.S. market for blue light protection products reached $890.9 million. According to the analysis, the market is growing because people use smartphones more frequently (yes, even in America) and because of the increasing hype around awareness of the problem.

Analysts say people are also starting to protect themselves from blue light with “botanical ingredients such as ginger, pomegranate, noni fruit (I had to google this one), and carrot root.”

As a proud owner of blue light-filtering glasses (I asked my wife for them without reading about them), sometime later, I decided to use my medical and non-medical knowledge and try to get to the bottom of the issue. So buckle up – it's about to get heated in here.

Literally me, when I read about the market size for noni fruit.

So, what is this blue light, where does it come from, and why is it everywhere? (literally)

(Not even) strangely enough, the most satisfying source on the basics of blue light was from Germany. It was not just German, but also an article in a Preventive Medicine Journal from ASU (“Arbeitsmedizin, Sozialmedizin, Umweltmedizin” - Occupational Medicine, Social Medicine, Environmental Medicine). The source is rock-solid, in my opinion. Make a note of this, and I’ll explain why later.

Nowadays, the primary source of blue light is LEDs (light-emitting diodes). They are used to backlight monitors, smartphones, and other tablets. To get such an LED lamp, the blue diode is covered with one or several fluorescent material layers (e.g., phosphor). These materials' fluorescence mixes with the diode's blue light, and we get a “normal” white light.

Many studies have examined the so-called “Blue Light Hazard.”

Preventive medicine experts (German ASU) reviewed all published studies with the keywords “blue light” and “review” they could find from a given period, combed through the articles for flaws, and highlighted the main points.

In short, researchers compared different light sources with a reference to halogen lamps (don’t ask why). Ready for results? At the same intensity, sunlight on a sunny day at noon affects the retina 2,6 times more than a halogen lamp. Your iPad Mini 2-LED screen affects the retina... 2,59 times more than a halogen lamp. But before panicking and throwing away your tablet, you must understand something. Some readers may have already noticed the trick here.

Remember I said to note why the primary source of blue light will never be the LED screen? Well, it’s also about intensity: On that sunny day, the sun shines with an intensity of 100,000 lux (lux is an international unit of light intensity), while a monitor screen at a distance of 50 cm at maximum brightness has an intensity near 500 lux. Think about that. That’s why, in 2019, the International Commission on Illumination assessed the exposure to artificial light as non-hazardous. 

But let’s dig deeper.

Many studies indicate that blue light is a risk factor for developing various eye diseases and retinal issues, BUT ONLY in experimental and animal studies. These data have not been confirmed in epidemiological studies. 

What did you just read? Let me explain.

We have a theory that blue light is harmful. But how to prove it? First, you experiment in a test tube - you take some cells and, in our case, expose them to the (blue) light and check what happened. 

If you get what you expected, you experiment on animals (unfortunately, this is an ugly reality) - now shine light into their eyes and check back later if there is any developed disease as a result. 

Proven? It's time to conduct epidemiological studies: look for the group of people exposed to a specific factor (in our case, this would be a group that received more blue light) and a group of people without or with less exposure (another group that received very little blue light exposure) and compare them. 

Suppose now, for example (in our case, it is not so), you got the result that blue light is harmful. But even this is not the end - after that, you start the “gold standard” - a placebo-controlled randomized trial. You take a group of people and check them from head to toe - is anyone sick? Pick only the healthy ones. Choose the most similar people (i.e. age, etc.), divide them into groups and shine an ordinary lamp (placebo) on some and a lamp with a blue filter on others. Your subjects don’t know which lamp they are exposed to, and you don’t know either - everything is encrypted (controlled). The results of such a study could be considered reliable (but not 100%!).

What? You thought it was simple? Pharmaceutical companies spend millions on such studies for their drugs.

So, the Germans conclude that blue light is not harmful (at the workplace). Remember I said to make a note? Why can this article be trusted? Well, believe me, getting a German to officially declare that ANYTHING at the workplace WON’T cause harm is sometimes a task for Tom Cruise’s team from “Mission: Impossible.” [click]

But let’s see what the French have to say.

ANSES—The French Agency for Food, Environmental and Occupational Health & Safety wrote in 2010 (based on an expert report) that blue light is toxic to the retina and recommends modifying regulations for LED light. In 2019, they released a new press release repeating and strengthening the recommendations of 2010.

In particular, they write about the high risk of blue light effects from specific sources: street lamps, car headlights, etc. They also write that blue light can affect circadian sleep rhythms (but this is a separate topic; here, we will focus on eye problems). The third problem the French see is “temporary light modulation”: the flickering of LED lamps, which occurs more frequently than in fluorescent and halogen lamps. Finally, they recommend reducing children’s exposure to blue light. [click]

The French report has a few nuances. To begin with, there are no references in the communiqué. It’s just a description of expert recommendations without referencing the experts themselves. I won’t mention that, theoretically, anyone could act as an expert. And nowadays, expert opinion is no longer the standard it used to be, at least in medicine. Even if you are a four-time professor with ten thousand articles of worldwide renown - your words are insufficient to make health recommendations — only properly designed trials, only hardcore.

Try applying this concept to any news or advice you read. Which information source is your reading based on? If there are no quality studies on the subject (which often happens), does it gather opinions from several independent experts? Think about it.

Want more expert opinions without direct references? 

Please: the American Academy of Ophthalmology (I am sorry, guys). 

Right on their website, they create a series of articles with ten internal backlinks (“Search Engine Optimization, do you speak it?”) [click]. And there, they categorically declare: “Blue light does not cause any harm to the eyes.” What intensity of light, for how long can one expose himself to it, till it (does not) cause(s) harm? Does blue light from the sun count too? These questions are irrelevant - the opinion has already been stated. What more do you need?
In the colleague's defence, informational sites like these may be specially tailored to cover the community more thoroughly. The complexity and references will be sacrificed in the name of a better understanding of the material (again, please, no offence, guys).

Finally, let's get to the golden part of our article: randomized trials. 

Yes, they have already been conducted. As always, there's a nuance with such studies, too. Look at the titles: 1. “Do lenses that block blue light reduce eye strain during prolonged screen use?” 2. “Does the iPhone “Night Shift” feature help reduce the effect of the smartphone on sleep quality?””[click, click].

You see the problem, don't you? We get an answer to one specific question in a specifically described situation. In the first study, researchers took similar groups of people, gave one group just the simple glasses, and gave another group glasses with a blue filter to work with their iPhones. 

In the second study, one group used iPhones with Night Shift on, while another group used them with this function turned off. 

All other situations with blue light are not considered and remain, so to speak, unclear. Logical chains need to be built, and you must draw conclusions.

Experiments in test tubes say “yes”, epidemiological studies say no, and randomized “gold” studies say eyes don’t strain when looking at an iPhone without lenses. 

Germans say that blue light at “low” levels is not dangerous, the French say blue light from “strong” sources is dangerous, and ducks say “quack.”

I’ll take advantage of writing this article and give you my opinion:

Blue light from smartphones, screens, and other tablets is not dangerous for the retina (or other eye structures). However, playing a staring contest with the sun, car headlights, and other intense light sources is dangerous. I would still consider (especially in the case of the sun) whether the light is dangerous, specifically due to its “blue” part or simply due to its intensity.

Working on a tablet, gaming at night, and watching TV shows on a smartphone before bed can disrupt the quality and structure of sleep. The question is whether the problem is with the fact that our brains are active during such an activity or is within the exposure to blue light. We can recall that people often read books in bed and sleep soundly.

If you want to protect your health, you can certainly use your smartphone's or PC display's built-in functions—they will bring you no harm (the protection functions). But I wouldn't spend money on specific filters or overpay for the extra “blue filter” function.

Instead of obscure diet with noni fruits and other carrots, I would engage in things that, although bland, are still effective for preventing eye (and other) diseases: sports, quitting smoking, the 20-20-20 rule: every 20 minutes, take a break from the screen for 20 seconds to look at an object 20 feet (6 meters) away.

You can also stretch your neck while looking out the window. The exercises I describe have been derived from long periods of well-designed trials.

Don’t rush to follow trends, especially when it concerns your health and isn’t directly recommended by your doctor. If you are checking the effectiveness of a particular product, look at what the information is based on. There’s a life hack for the very lazy - try to get info from “.org” pages – these are usually non-profit organizations. I would be cautious with open-source projects like Wikipedia - you sometimes must review the sources thoroughly.

This field fascinates me - all kinds of “ergonomic” chairs and keyboards - do they work? What is harmful about prolonged sitting in front of a PC for the eye, and what solutions already exist (spoiler: computer vision syndrome)? The (un)usefulness of various supplements and other dietary supplements. 

Write in the comments what would be interesting to you.