This article has been reproduced with the kind permission from Alex Fergus from AlexFergus.com . It has been edited minimally. Read the full article here – https://www.alexfergus.com/blog/ultimate-blue-blocking-filter-guide
Sometimes it’s difficult to distinguish insanity and cleverness.
This, for example, is me after sunset:
I must be weird? Crazy? Or do I know something other people don’t?
The answer is a resounding yes (to all questions)!
In that picture, I’m wearing what are called “blue blocking eyewear”. I always wear these blue-blockers after sunset.
Well, these glasses block all blue (and most green) light. In other words, blue and green wavelengths of light do not enter my eyes after sunset.
( RLR DayPRO Lenses block 95% of blue light & NightPro Lenses block 100% of blue and green light)
You’re probably thinking “what is blue and green light?” And “why do I need to block blue and green light?”
Well, let me tell you about light.
When blue and green light enter your eyes, they have a huge impact on your biology. So light not only illuminates the room, but affects your body’s biology as well.
Here’s why light is interesting:
Wearing these glasses after sunset results in more energy during the day, deeper sleep, clearer thinking, and improved well-being.
How do these blue-blocking glasses exactly improve energy and mood? That’s what I’ll tell you in this blog post.
- First disclose a story about how and why I developed this “weird” (but necessary) habit.
- Then dig deep into the science of blue and green light (mostly for the nerds out there).
Have you fastened your seat belts?
I promise one thing:
After reading this whole post, you’ll want to be a weirdo too.
Let’s start with my story.
My Story About Not Filtering Blue And Green Light
It was 3AM. Tuesday night. Reading on the internet.
Time to go to sleep.
But I could not sleep (yet).
For years, I had convinced myself that I’m a “night owl”. I had convinced myself that it was “normal” to stay up until 1AM or 3AM. I had convinced myself it was normal not to be tired late in the evening.
I also thought it was normal that you could not sleep immediately in the evening.
I was wrong.
You see, you are supposed to get tired during the late evening. And the other side of the equation entails that you are supposed to have plenty of energy during the day.
Because I stayed up until late at night, I thought I had great energy. In my mind, I linked having great energy to being able to stay up late.
I was wrong again.
Being young, I probably got away with sitting in front of a computer late at night. Since then, I’ve nevertheless corrected that (bad) habit.
Breaking that bad habit allowed me to improve my energy levels enormously.
So can you.
Why settle for less energy if you can have a (lot) more?
You see, light exposure during the evening and night was an elephant in the room that I did not take into account back then.
That elephant is overlooked by everyone in modern society. That elephant causes your energy levels and health to be lower than they can be.
You can see it this way:
Staying up until 2AM or 3AM only gives you the illusion that you have great energy levels. But it’s only the artificial light allows you to stay up that late.
When not exposed to toxic artificial light, you’ll automatically go to sleep during the late evening.
The toxic light sources that we are exposed to after sunset include:
- Ad screens
- LED lighting
- Street lighting
Don’t get me wrong. Most artificial light is bad for you during the day as well. But artificial light is especially toxic at night.
Why can artificial light be toxic? All of these previously mentioned light sources put out tremendous amounts of blue and green light.
But let’s first return to my story.
When I was sitting in front of my computer screen at 3AM, little did I know about the extent that light influenced my sleep quality. Even though I was young, I did not sleep as well as I could.
Like most people, I just did not feel the effects of blue and green light.
For most people, the effects of light during the night are very subtle.
Most people never learn about how much blue and green light destroys their sleep quality until they start actually blocking blue and green light.
You cannot rely on your feelings regarding how blue and green light are influencing your sleep quality.
One of the most common arguments I get from people, is that they already sleep well, or already have great energy. They say:
“But Bart, I don’t need blue-blocking glasses. I already sleep well!”
They assume that they can get away with blue and green light exposure at night. These people assume that they do not need blue-blocking glasses.
With all empathy, I’ll say that their conclusion is incorrect.
The fact that you do not feel light influencing you does not mean that light does not influence you.
Let’s explore that argument.
Why You Won’t Feel You Need Amber Or Red Glasses
Human beings are great at perceiving when something changes.
But you probably no longer perceive anything that has stayed the same for long periods of time.
That’s why you cannot always feel what is happening inside your body. Or perceive something that is happening right before your eyes. Even though something might be slowly killing you.
The solution is that you must test whether something is influencing your biology – such as blue and green light.
Only testing will give you clarity – quantification.
Let me rephrase that statement:
Only after testing blue-blocking glasses will you realize that blue and green light exposure after sunset are lowering your health.
How do I know that our feelings lie in relation to health?
Well, let’s look at some examples:
- You might feel that you’ve gotten “used” to eating large amounts of unhealthy vegetable oils (commonly called polyunsaturated fatty acids).
- You might feel that you’ve gotten “used” to living in areas that contain lots of pollutants, such as inner cities.
- You might feel that you’ve gotten “used” to never moving or exercising
- You might feel that you’ve gotten “used” to eating excessive sugar.
In essence, most people no longer feel the difference between healthy and unhealthy behavior.
The same is true for our light environment.
You might feel that you’ve gotten “used” to being around toxic amounts of blue and green light at night. You might feel that blue and green light do not harm you.
That feeling doesn’t tell much…
And no, I don’t have a problem with feelings. I just have a problem with people not measuring how something is affecting their health. That’s why you must always investigate your feelings, in the same way you investigate arguments and presuppositions.
Feeling can be incorrect just like propositions…
The previous air pollution example is a great analogy as to why you cannot conclude on the basis of feelings that blue and green light do not harm you.
Let’s say you’re living in a polluted city. In that case, you might need a week of camping in nature to realize that the air pollution was ruining your health in the first place. Air pollution will cause:
- your sinuses to be chronically congested
- your breathing patterns to be poor
- your energy might be lower than they should be
- you to feel bad all the time
Only after camping for a few days, will these symptoms “magically” go away.
And you’ll only conclude that after testing.
You’re not alone in this realization that testing is important…
This lesson was true for me as well.
For a long time, I knew that blocking these light frequencies might help. I’d read about blocking blue light on several websites but never tested the assumption. But I only became fanatically convinced that these light frequencies damaged my energy and sleep after blocking them for some time.
Why do blue and green light matter that much?
Well, let’s have a deep look at what blue and green light are. That way, you can better understand why both are damaging you after sunset.
You’ll later learn how to avoid exposing yourself to these frequencies during the evening using blue blocking glasses
The Light Spectrum And Human Evolution: Why Blue Blocking Glasses Are Necessary
To investigate blue and green light, we have to take a look at the “light spectrum”.
At first sight, the term “light spectrum” seems difficult. Nevertheless, everyone is acquainted with that light spectrum.
Just have to look at the rainbow’s colours:
Those rainbow colors make up all the colors of what is called the “visible light spectrum”.
The word “visible” here means that the light is visible to the human eye. As you can see, the main colors contained in the rainbow are:
Different colors have different wavelengths.
Let’s explore that light from a physics perspective. From a physics perspective, each color has its own wavelength(s). These wavelengths are measured in nanometers.
Wavelengths between 400 and 700 nanometers are visible to the human eye. So all the colors between purple and red can be found between the 400 and 700-nanometer range.
Red light, for example, is located between 620 and 700-nanometer wavelengths. Blue and green light, are located between the 425 and 600-nanometer wavelengths.
Below 400 nanometers, there is are the ultraviolet wavelengths. And above 700 nanometers, the infrared wavelengths are found. Both ultraviolet and infrared are invisible to the human eye.
For the current article you’re reading, the ultraviolet and infrared parts of the light spectrum do not matter that much. In this blog post, I’m focusing mostly on blue and green light.
But just to give you a complete overview, you can see the relation between the colors of the rainbow (the visible light spectrum), ultraviolet light (UV), and infrared light (IR) here:
Why am I telling you about the wavelengths of visible light? Because different light wavelengths have unique biological effects.
As human beings, we’ve evolved to be exposed to certain frequencies of light at very specific times of the day.
So, there’s a specific time of the day you should be exposed to blue and green light. And there are specific times of the day you should not be exposed to blue and green light.
As an example, just have a look at this African tribe:
These people live with the sun. When the sun comes up in the morning, they wake up. Several hours after the sun comes down at night, they go to sleep.
Because they live under the sun, they are almost exclusively exposed to the light spectrum of that sun.
Let’s talk about the sun’s light spectrum, and why that light spectrum matters.
The sun emits a lot of blue and green light during the day. The higher the sun moves up in the sky, the more blue and green light reaches the earth’s surface.
In simple terms, blue and green light are only present when the sun is higher up in the sky.
Here’s how these wavelengths relate to sunlight, specifically:
(You can see the light spectrum of the sun during the afternoon in the picture below. Observe that there is a lot of blue and green light (425-600nm) during that period.
This graph displays the sun’s light emittance that reaches the earth during the mid-day. The light spectrum of the sun at sunrise is very different than the light spectrum at noon.
During sunrise, a lot of red and infrared reaches the earth’s surface, but less blue and green light.
The same spectrum is present during the period before sunset. With blue blocking glasses, we’re trying to prevent simulating noon (at night), by blocking the blue and green frequencies. Most artificial light in your environment emits lots of blue and green light.)
Conclusion? Blue and green light emitted by the sun are only present during the day. Blue and green light give your body the message that it’s daytime.
Remember the African tribe example from before?
These African tribes are exclusively exposed to blue and green light during the day, because they do not have any artificial light (other than campfires). Their campfires do not emit any blue or green light, but just red (and infrared) light.
That red and infrared light does not affect your sleep.
So, the people living in the African tribe are never exposed to blue and green light at the wrong times.
You, as part of our “advanced” and “modern” society, however, are exposed to blue and green light at night everywhere you go. Smartphones, television screens, and artificial lighting, are exposing you to lighting conditions that have never existed for humanity before.
For hundreds of thousands of years of human evolution, we were never exposed to blue and green light during the late evening or night.
However, the artificial light that emits a lot of blue and green light has only been around for more than a few decades.
The evenings of your ancestors were thus fully free of blue and green light. Even 150 years ago, our evenings were free of blue and green light.
The light in your environment is thus very different than the previous billions of years.
Now that you understand how blue and green light at night is a new phenomenon, let’s look at why they make you sick at night.
How Blue And Green Light Influence Health – And Need To Be Filtered
We slowly get to the clue of this story.
Light in our environment does not only work as illumination, but light has biological effects. In nature, blue and green light are only present during the daytime. Artificial light has made blue and green light available 24/7 in our society. Artificial light makes your brain think it’s daytime.
What do I mean with light having “biological effects”?
Let me give an example.
You probably know about the biological effect of ultraviolet light. Most of us have experienced a sunburn at some period of our lives, because we stayed in the sun for too long. That sunburn is direct proof for you that light has biological effects.
It’s a simple cause and effect relationship.
You got exposed to light, and the biology of your body was influenced.
Before getting into the sun, your skin was normal. And after staying in the sun (for too long), you became and stayed “red”. Conclusion: you have already experienced the biological effects of light.
Most people think that only ultraviolet light has biological effects. But to the contrary, all wavelengths of light have biological effects.
In your body, there are two main mechanisms for light’s biological effects:
- Light that enters your skin
- Light that enters your eyes
You are probably consciously aware of the first mechanism – our skin – if you have ever experienced a sunburn.
However, you might also be aware of the second mechanism – our eyes – but in a different manner.
How are you aware of the biological effects that light has through your eyes? Well, you probably turn the lights off when you go to sleep at night.
Turning off the lights before sleep means that you’re at least subconsciously aware of the biological effects of light via your eyes.
You thus already know that it’s harder to sleep under bright light. What you are probably are not aware of is the massive extent to which light influences your biology through your eyes.
In reality, when light hits your eyes, the effects of that light can last for hours.
So, just turning off the lights when you go to sleep is not enough to get great sleep. Instead, blue and green light need to be absent from the eyes for several hours for optimal sleep quality to be possible.
Remember your ancestors. These people were not exposed to blue or green light after sunset at all.
It is the absence of blue and green light causes buildup of the hormone melatonin in the brain.
Blue and green light exposure to the eyes, on the contrary, prevent melatonin buildup.
An example: let’s say that you’re exposed to blue light at 9 PM. That blue light consequently affects when you want to go to bed at 11 PM.
Without sufficient melatonin in your body, you won’t have an optimal sleep quality. And with low melatonin levels in your brain, you will [1; 2]:
- take longer to fall asleep
- sleep less deeply
- have a shorter total sleep duration
The human eye is absolutely central to increasing melatonin levels:
Your eyes not only allow you to see.
Your eyes also signal to your brain whether it’s night or day.
The eyes help to signal whether it is daytime or nighttime via the brain when blue and green light affects them. That light reaches your brain and affects what is called the “circadian rhythm”.
The circadian rhythm stands for a 24,2-hour “master” clock in our body. That master clocks keeps track whether it is day or night in your body. Blue and green light influence that master clock.
If you’re getting blue or green light through the eyes at 11 PM, your brain will think it’s noon. To reiterate:
The more blue light and green light enters your eyes, the more your brain will think it’s time to wake up.
If blue and green light do not enter your eyes, your brain will “think” it’s time to wind down for the night.
Melatonin is a key hormone in this circadian rhythm. Besides sleep quality, melatonin is responsible for lots of processes in the human body.
Here’s why Melatonin matters:
Proper melatonin functioning is necessary to stay healthy, as:
- High melatonin levels are associated with preventing cancer [4; 9]. Having higher melatonin levels in your body seem to inhibit tumor growth, and prevent tumors from “spreading” into other areas of the body .
- Melatonin plays a major role in our immune system [6; 7].
- Low melatonin levels are associated with sleep deprivation [3; 8]. And sleep deprivation, in turn, lowers your ability to think clearly. Sleep deprivation also lowers your physical performance.
- Higher melatonin levels are associated with better moods .
- Melatonin will help prevent and treat cardiovascular disease [16; 17; 18; 19]. Melatonin improves cholesterol levels, lowers blood pressure, decreases stress hormones,
- Melatonin may help prevent autoimmune diseases, such as Parkinson’s disease, fibromyalgia, or MS [11; 12; 13]. These effects, however, have currently mostly been demonstrated in animal studies.
- Melatonin lowers pain and anxiety [14; 15]. Even traumatic stress might be lowered through returning the body to the right melatonin levels.
You need the right melatonin levels in your body to sleep well and be healthy. There’s no way around having optimal melatonin levels in your brain at night, if you want optimal health.
The best way to keep your natural melatonin levels high is to buy a high-quality blue-blocking glasses.
Hence, there’s no avoiding blue-blocking glasses if you want to achieve optimal health in modern society.
You need blue-blocking glasses.
Without blue-blocking glasses, you would have to exclusively expose yourself to campfires and candles after sunset. All other light sources would have to be eliminated. Exposing yourself exclusively to campfires and candles after sunset basically means that you cannot eave the house – there is light everywhere in our modern society at night.
If you’re exposed to light, there there are no viable alternatives to wearing blue-blocking glasses.
But let me build an even stronger case for the necessity of blue-blocking glasses in modern society:
Why Blue Blocking Glasses Are Essential For More Than Just Melatonin
I can already hear you ask: “but Bart, can’t I just supplement with melatonin instead of wearing blue-blocking glasses?”
The answer is no…
In fact, the effects of light reach much farther than just affecting your melatonin hormone levels. Light influences other hormones as well, such as cortisol, growth hormone, and testosterone [20; 21; 22].
Blue light can even raise your insulin and blood sugar levels [23; 24].
Supplementing with melatonin will not prevent blue and green light from influencing all these other hormones. To avoid the negative effects of the persistent light that’s everywhere in our society, you’d have to supplement to control all these other hormones as well – such as cortisol and insulin.
Controlling so many hormones through supplementation is impossible. So, if you want optimal health, you need to wear blue-blocking glasses at night.
You thus have to choose between:
- Looking weird while wearing blue-blocking glasses, but moving closer to optimal health
- Looking the same as “normal” people, but having much lower sleep quality and energy due to blue and green light
Air pollution or smoking are – again – great analogies here.
For decades, it was very hard to avoid cigarette smoke when you left the house.
People smoked everywhere:
- At the train station
- In their homes
- At work
- In public buildings
But if you wanted to avoid the negative health consequences of the smoke, you still had to avoid exposing yourself.
You were probably considered weird back then if you refused to live in buildings polluted by smoke.
The same is true for blue and green light:
Most people in society will think you’re weird when wearing blue-blocking glasses.
But you need to wear these glasses for optimal health. You have to protect your sleep, energy, and health.
Health should always have your first priority. Without health, you cannot achieve or do anything in life.
Now that we’ve concluded that melatonin supplementation will not give you the benefits of wearing blue-blockers, let me give you one last reason why blue-blocking glasses are absolutely necessary in modern society.
Blue Light Glasses: Protecting Your Day And Night Cycle
Even if you thought it was impossible, the story turns worse. There’s an additional problem with our society’s evening and night illumination.
You see, there’s not just one day and night cycle in your body. There are many day and night cycles.
To explain why there are several day and night cycles in your body, let me give you another analogy.
Remember the previous master clock in your brain. That master clock is the main governor of your circadian rhythm.
The word “circadian rhythm” here, can be understood as your day and night cycle – or light and dark cycle.
But next to that “master clock”, each and every cell of your body contains its own circadian rhythm – its own individual clock .
So, every cell in your body has its own day and night cycle. And all your cells’ day and night cycles are influenced by light:
Light influences the “Master clock” in your brain
Light influences the clocks in your cells
All these clocks need to work together for your body to perform optimally. When you expose yourself to light at night, this means that there will be a fundamental mismatch between the master clocks and the other clocks in your body.
Imagine the mismatch this way:
Your main master clock is influenced by light that enters your eyes. If blue and green light enter your eyes at night, those light frequencies will alter the time displayed at that master clock.
The master clock in your brain will no longer display the same time as the clocks that can be found your body’s other cells.
If the clock inside your brain and clocks inside your cells are not synchronized, then problems emerge.
In that case, your body will:
- get more inflamed 
- be at higher risk to get autoimmune diseases 
- get heart disease sooner 
- have more risk to get cancer 
You thus need to protect your body’s clocks, by exposing your body to the light stimuli it has evolved under.
The timing your body is exposed to light needs to be correct.
Let’s make another analogy here.
That analogy will help you understand how these different clocks in your cells and the master clock in your brain work together.
Let’s say you’re leading a sports team.
As a leader, you’re analogous to the master clock. The other team members are analogous to the different cells in your body, which are all exemplified by their own clock. If your timing as a leader is different than the other team players, there will be problems:
- You’ll give the wrong command at the wrong time.
- You’ll pass the ball at the wrong time
- You’ll move in the wrong direction in relation to the other players
- Communication between players becomes impossible
Finally, playing the game becomes impossible.
If you are exposed to blue and green light at night, the same “miscommunication” happens between master clock in your brain and the clocks in your body’s cells.
For optimal health, the master clock and the clocks in your cells need to be able to communicate. And to communicate properly, these clocks need to run synchronously.
Simply put, all your body’s clocks need to display the same time. Light manages the time these clocks display.
All these clocks have evolved to be exposed to sunlight during the day, and have evolved to be exposed to darkness (an absence of light) after sunset .
A high-quality blue-blocking glasses is the best way to protect your body against the harmful effects of too much toxic light at night.
Here’s where we see the second problem with melatonin supplementation:
Melatonin supplementation cannot prevent the problem of the clocks no longer running in synchronicity.
Let’s look at why our modern environment almost ensures that our Master clock and clocks in our cells miscommunicate.
It’s not just smartphones and tablets that emit lots of light at night. You’re not even safe from blue and green light outside your home, due to all artificial lighting.
Your ancestors did not evolve under this “night” sky:
Instead, your ancestors evolved under this night sky:
Your body is built (by evolution) to sleep under the latter sky.
The amount of light intensity in cities, however, is currently at least 30 times as great as before the invention of modern artificial light . Other calculations paint an even worse picture.
Sitting close to an average lamp at night, for example, can bring about light intensities that are millions of times as bright as the night sky of our ancestors .
All that light creates a mismatch in your biology.
It’s very sad that there’s no real night sky in the “civilized” parts of our planet anymore. The same problem is true for the inside of our homes.
Americans currently own 3.64 digitally connected devices per person . That number does not even include televisions. All these devices put out massive amounts of blue and green light.
What’s worse is that blue and green light is even more damaging to your children than adults .
Most children grow up with these devices nowadays. They should not.
But to return to the problem of blue and green light at night:
Even if you dim your indoor lights, they still influence the circadian clocks in your body. Outdoor lights are equally problematic.
Your eyes need darkness though.
To simulate that total darkness, you thus need blue-blocking glasses at night.
There’s no cop-out.
There’s no supplement you can take to avoid wearing blue-blocking glasses.
(You also need to cover up with clothing at night, but that will be a topic of a subsequent blog.)
Scary right? It was for me too. But I’ve accepted that I need to wear blue-blocking glasses during the night.
I hope I’ve convinced you that blue-blocking glasses are a must.
Solution: High-Quality Blue Blocking Glasses
I would not help you if I only described a problem, without offering a solution.
So here’s the solution:
I’ve done all the research, and can make the recommendation that helps you get the best blue-blocking glasses. I’ll make you a promise: on this blog: I’ll only recommend the best products for you.
I’ve looked at many different blue-blocking glasses brands. I’ve long searched for the highest quality.
For me, those high-quality blue-blocking glasses have a few requirements:
- The blue-blocking glasses should be effective at blocking both blue and green light. Most blue-blocking glasses fall short of blocking green light. Most commercially available blue-blocking glasses do not even block all blue light either.
Additionally, there are a lot of misleading advertisements regarding how well blue-blocking glasses work. Sometimes a company claims that their blue-blocking glasses block 100% of blue light, while in reality, the glasses only block 70%.
When blue-blocking glasses do not block 100% of blue light, this will be problematic for your biology.
- The blue-blocking glasses should look good enough to wear outside the house.
To be frank, most blue-blocking glasses look absolutely terrible.
I consider myself to be pretty ballsy, but I would not leave the house with blue-blocking glasses that look like I just exited a factory.
Hence, blue-blocking glasses need style.
I know that style is important for many other people. I’ve talked to many people over the years about blue-blocking glasses. I know that many people think style is very important for choosing a blue-blocking glasses.
You might be one of these people who think a stylish design and frame is important.
So, if possible, the company selling the blue-blocking glasses should offer multiple models and frames to accord to the different tastes that people have.
Blue-blocking glasses should just look damn good.
- The blue-blocking glasses should be easy to order.
No appointment in a physical location should be needed to order the right model and prescription that you need.
Everyone should be able to order a blue-blocking glasses online.
This criterion disqualifies most national and local shops. I want to be able to offer high-quality blue-blocking glasses to anyone living in the civilized world.
Blue Light Filtering: My Final Results
Since switching to blue-blocking glasses, I will never go back anymore.
Lots of others in the health community actually share my sentiments.
What’s more important is this:
Even a single night of improved sleep because of wearing blue-blocking glasses can give you great results [33; 34].
Try it. You have nothing to lose. You don’t have to wait for 2 weeks to feel the results.
And you need to test blue-blocking glasses to find out how much better they make you feel.
Returning to the argument I made before, you can only trust your feeling once you can compare between alternatives.
And just to rephrase the message one more time: the only way to realistically block blue and green light in modern society is to wear blue-blocking glasses–or you can just live under candlelight after sunset.
The choice is yours.
Conclusion: Bring On The Amber Glasses Revolution
Let’s go over the argument one more time.
The main clock in the human body is located in your brain. That clock reacts to light.
That clock also needs to stay close to the day and night cycle under which we have evolved as human beings.
To stay close to the light and darkness cycle that humans evolved under, you need blue-blocking glasses. Blue-blocking glasses will keep the main clock in your brain, and the other clocks that are located in all the cells of your body synchronized.
If these clocks run at different speeds, due to the influence of light, health problems arise.
Please don’t take away the message that blue and green light are bad for you. Blue and green light are great for you during the day – especially when they come from sunlight.
But blue and green light at night will lower your melatonin production dramatically. Blue and green light at night also influence other hormones in your body.
And with bad hormonal functioning, your health will suffer.
Blue blocking glasses:
You just have to be a bit weird to be healthy in modern society.
You have to take a stand.
You have to make a choice.
Use our code BLUEBLOCK for an exclusive discount and explore our range of blue blockers now here.
This is a post by Bart Wolbers. Bart finished degrees in Physical Therapy (B), Philosophy (BA and MA), Philosophy of Science and Technology (MS – Cum Laude), and Clinical Health Science (MS), and is currently the chief science writer at Alexfergus.com.