Blue light is present in sunlight (which is cool white – just to heighten the concerns). Moreover, blue is one of the three primary colors. Without it, you can’t mix turquoise, purple, or even trendy pink – and white wouldn’t exist either. So, the sun shines with all the colors of the rainbow, which are filtered (and refracted) by the atmosphere, reflected by the environment, and the result is a clear noon sunlight – cool white.
In the image below, you can see the spectrum of daylight sunlight: – around 5600 Kelvin
I stole the images, drew on them, edited them to make them somewhat uniform in appearance.
You can see somewhat similar images in many places, but I dare not claim any of them to be absolutely accurate, and depending on environmental conditions, every such measurement will be slightly different. So, the light of the noon sun consists of such strength variations and such color spectrums.
If there is so much blue light in sunlight, is blue light good or bad?
Opinions are divided on the beneficial and harmful effects of blue light.
- Good, because blue light can be an effective tool in fighting winter depression and insomnia.
- Light not only aids better visibility but also plays an important role in regulating our biological rhythm and impacts our general well-being. Light influences whether we are awake or asleep, allowing us to focus on our work, be efficient, and feel refreshed and healthy. – (2)
- Scientific studies have proven that light has biological effects on our bodies. UV light, for example, participates in vitamin production. Exposure to strong, especially blue, light affects our hormone balance. The body’s hormones regulate mood and circadian rhythm. The amount of blue light should be relatively high during the day and significantly lower in the evening. – (2)
- When the sun is shining outside, the body releases serotonin (also known as the happiness hormone) and cortisol (the stress hormone). Both hormones make us feel alert and active. Melatonin, on the other hand, is the so-called sleep hormone, which makes us feel tired in the dark and sleep deeply.
Light, and particularly blue light affecting our retina, also influences our psychological health. This is why light therapy is successful in treating winter depression and insomnia. – (2) - Morning wakefulness is helped by the blue wavelength of sunlight, which triggers the release of serotonin and dopamine neurotransmitters, as well as the hormone cortisol. In the evening, when the natural level of blue light decreases and is replaced by dim red light, melatonin is produced, helping us to fall asleep. Complete darkness is needed at night to initiate cell renewal processes. – (4)
- Bad, because blue light can permanently damage our vision.
- It strains the eyes. Responding to a 2018 study conducted at the University of Toledo, one professor said: “It’s no secret that blue light damages our vision by harming the eye’s retina.” While scientists find the negative effects of blue light on our eyes concerning, it remains controversial whether the amount emitted by electronic devices reaches the threshold that truly causes problems. The aforementioned professor, an assistant professor at the university’s Department of Chemistry and Biochemistry, is also worried about the increasing prevalence of age-related macular degeneration and hopes that soon a way will be found to protect the eyesight of children born and growing up in a high-tech world. – (1)
- It disrupts our sleep cycles. Nighttime light, especially blue light, can disturb the 24-hour cycles of our body, known as circadian rhythms. One of the most important of these for humans is the alternation of sleep and wakefulness. If we are exposed to light at night, it inhibits the release of melatonin, the hormone responsible for regulating our circadian rhythm. If we are exposed to blue light at night, it has an even stronger effect, inhibiting melatonin production for about twice as long as green light. In short, exposure to nighttime light, especially blue light, can prevent us from getting the proper amount of sleep, which can lead to numerous negative health consequences. – (1)
- When people are exposed to artificial blue-rich white light at night from screens, electronic devices, and artificial lighting, the light-sensitive ganglion cells in the retina signal the brain to stop producing melatonin. Such disturbances can have wide-ranging effects: on sleep and wake cycles, eating habits, metabolism, reproduction, mental alertness, blood pressure and heart rate, hormone production, temperature, mood patterns, and the immune system. – (4)
Problematic Parts of the Visible Light Spectrum
The visible light range is within wavelengths of 380 to 780 nanometers. Anything shorter is ultraviolet (UV light) and longer wavelengths belong to the infrared range (IR light), which we cannot see.
The following diagram from zeiss.hu illustrates the details well.
zeiss.hu – (2)
Experts have known for some time that UV light can be harmful to biological tissue, such as the skin or eyes. Generally, we protect ourselves from the sun using sunscreen or sunglasses. However, visible blue-violet light can damage the eyes. While blue-violet light is lower in energy than ultraviolet light, it passes almost completely unfiltered through the eye, reaching the retina. In contrast, the eye’s front part absorbs almost all of the ultraviolet light, and less than 5% reaches the retina. Too much ultraviolet and blue-violet light can harm the human eye. Besides causing painful inflammation of the conjunctiva and cornea, it can damage the lens (e.g., cataracts) and especially the retina (macular degeneration). – (2)
The blue component of light in the 380 to 500 nm range is called high-energy visible (HEV) blue light. Blue-violet light in the 380 to 440 nm range is particularly harmful and is likely one of the causes of photoretinitis, damage to the retina caused by high-energy incoming light. – (2)
The ability to produce artificial light has allowed people to spend more time indoors. Some studies suggest that Europeans spend 90% of their time indoors, often under artificial light, a significantly different environment from the natural conditions (outdoors). The first mass-produced and widely accessible artificial electric light source was the incandescent lamp. – (3)
For over a century, incandescent light sources served us well. These bulbs were cheap to produce and dispose of, and easy to dim. Their spectrum is continuous and contains most colors of the rainbow, similar to a sunset – (they were poor in the blue range). Due to concerns about the energy demands of incandescent lamps contributing to global warming, decision-makers, such as the European Commission in 2009, began phasing out incandescent lamps from the European market. – (4)
Hopefully, it is clear to everyone from comparing the spectrum images that the rainbow colors do not match the indicated wavelengths in every image. In reality, it is advisable to focus on the wavelength values and the height of the curve. This rainbow coloring is mainly to show the wavelength trend, and it is more decorative.
For example, it is immediately apparent in the image above that the creator forgot to include the green color in the rainbow representation. I saw the mistake and used it anyway.
It can be seen that the spectrum of a traditional bulb is very similar to the spectrum of sunset light, so from this perspective, using it in the evening before going to bed is the most natural artificial solution.
It is important to note that our eyes are exposed to 30 times more blue light in one hour spent outdoors on an average cloudy day than in one hour spent in front of a monitor. – (2) This is where my cynicism comes from – aren’t we overreacting a bit about this blue light?
Children’s eyes do not filter blue light as well as adults’. If they spend too much time in front of screens, it can increase their chances of obesity, myopia, and attention disorders. – (5) This is another thought that has affected me. The first sentence is okay, probably true, I don’t doubt it, but what does it have to do with the second one? It doesn’t state it explicitly, but it suggests that blue light causes the problems mentioned in the second sentence. What is this if not a misrepresentation? Why, if the screen they watch a lot didn’t have blue light, wouldn’t these problems exist? Of course, they would. If a child spends several hours a day motionlessly watching dynamic images, then, of course, they will get hyperactive afterwards to process the events and make up for the hours spent motionless. If they don’t, they will gain weight because they will still eat.
The light emitted by LED bulbs disrupts our sleep. Some LED bulbs are more disruptive than others, but with a few exceptions, most emit too much stimulating blue light to be safely used at night. … Exposure to blue light at night inhibits our melatonin production and signals alertness, disrupting our sleep and health. To sleep and feel well, we need strong light during the day and “biological darkness” at night! – (6) From two quotes above, it is clear that we don’t yet know how much is too much, probably significantly individual-dependent, just as there are night owl and early bird types of people.
The following linkable sources were used for the above section. Where numbers are found at the end of sentences or paragraphs, the sentences or images used come from the following sites, where further detailed information is also available:
- (1) – officedepot.hu
- (2) – zeiss.hu
- (3) – newtechnology.hu
- (4) – nature.com
- (5) – gyogyzona.hu
- (6) – sunlightinside.com
Let’s look at LED light sources in more detail
The light spectra of LED lamps shown below are spectrum images of products available in online stores, uploaded by manufacturers to eprel.ec.europa.eu, the European database for products requiring energy labels.
Cool White LED
The following image shows the spectrum of the most concerning LED lamp, the cool white light. They solved achieving the cool white color temperature of the LED with this massive blue spike, as without it, the lamp would be significantly warm white.
The cool white LED has the largest blue spike. In the highlighted 380-440nm range on the spectrum, it is evident that despite the high blue proportion, this purplish-blue range is negligible, which is considered one of the causes of cataracts or macular degeneration. Practically, the cool white LED emits minimal light in this wavelength range. This is especially true when we consider that we want to use cool white LEDs to replace daylight, i.e., to illuminate work areas. Compared to daylight (the first image), the sun emits significant amounts of such rays.
The second range, the 440-500nm turquoise blue band, is responsible for our circadian rhythm. The spike falls into this range and is strong in cool white LEDs. This is what scares many people. In reality, you just need to use the cool white LED properly. It keeps you awake, helps you focus on work or study, because it illuminates as if it were daylight when we are most active. Look again at the first spectrum image and realize that this blue is also the strongest range in daylight, just wider. So, if you use this in the evening before bed or overuse it for work, of course, you won’t be able to sleep normally, or you’ll have strange dreams, as your rhythm is not accustomed to falling asleep immediately after turning off the light following the most active period.
If you’re still pondering that this blue is huge, then consider that a well-lit desk has 500 lux illumination. If you go outside in the summer to mow the weeds, there can easily be 20,000 lux illumination. That’s a 40-fold difference. So now magnify the daylight spectrum image 40 times higher and leave the LED unchanged. Now, where is more blue? You might say, well, the proportions to other colors matter. Okay, the cool white LED is generally 6000-6500 Kelvin. Daylight (the first spectrum image) is 5600 Kelvin. But the midday sun is not always this. If you hike in high mountains or sunbathe on the beach, the color temperature can be 15,000-20,000 Kelvin. It’s so blue that if I found a spectrum image, you could see how huge the blue proportion is (not hard to imagine due to the blue sky and sea) compared to warm colors. And interestingly, we still feel good.
So primarily, it’s not the cool white LED that’s bad, but using it in the wrong place.
Non-LED
If you think the blue spike of the LED is nonsense compared to the nice spectrum curve of the sun, then see what other light sources can do. These also have multiple variants, so some spectrum images within the same lamp type can vary, but consider these generally spiky and jagged.
The fluorescent lamp, whether compact or not, among these, you can find very poor and quality ones, the mercury vapor lamp, which you now only find where the municipality had no money, the sodium lamp that makes everything on the street look yellow, and the metal halide. The four selected ugliest ones.
Neutral White LED
Initially, only cool white and warm white LEDs were manufactured, but about 12 years ago, neutral white color temperature LEDs also appeared.
It is usually called natural white because it sounds good. But what makes it more natural than the light of the noon sun or the light of sunset? – NOTHING. It’s somewhere halfway between these two. Why is the sunlight at 16:30 more natural? It would be more accurate to call it “neutral white,” and many correctly do so. Some call it “daylight white,” but the professional consensus is that daylight is referred to as cool white. However, if cool white is not sold, then “daylight white” sounds much better than neutral white. There are also companies that correctly call cool white “daylight white,” and to complete the confusion, they call neutral white cool white. In our online store, we arbitrarily named everything between warm and cool white as neutral white to avoid misunderstandings.
It can be seen that in classic neutral white LEDs, the blue spike is already smaller than that seen in cool white. Not as much blue needs to be mixed in, as we are approaching sunset, but the blue spike is still quite prominent.
Some LED manufacturers, addressing the issue of blue light, have developed solutions. The next image shows a neutral white LED from the Emos True Light LED product family. With the True Light LED product family, the manufacturer aimed to create more eye-friendly LED products. They reduced the blue range – you can see that the blue peak is flattened, filling the adjacent green dip, so the path to the peak of the yellow-red mound is smoother via the higher green. If we look at the first spectrum again, we can see some similarities, but this does not have the harmful bluish-purple part, and the peak is not blue but red. This makes sense since it is not cool white but neutral white. This LED family is not only eye-friendly, as seen in the spectrum, but also ensures no flicker and has a high CRI value. For our eye health and well-being, it’s not just the blue colors that can cause problems, but also the flicker of light sources and a poor CRI value. The CRI, or Color Rendering Index, for these LEDs is an excellent 94. Nowadays, LEDs usually reach or exceed a value of 80, which indicates a good CRI. Poorer quality LEDs exist, even around 70, but these are generally found in “cheap” street lighting solutions. Older fluorescent solutions had CRI values of 50-70, sodium lamps had 25, and traditional incandescent bulbs had 99 (the king and the sun) – but that’s another topic. Let’s move on!
Warm White LED
Naturally, the blue spike in warm white LEDs is even smaller, almost negligible. However, as seen below in the True Light LED type, the manufacturer did not stop at making it more eye-friendly. The small blue spike was further flattened. It is also noticeable that the peak was broadened towards both green and red. This was necessary in both directions, as they did not want to deviate from the 2700 Kelvin color temperature.
The Emos True Light LED product family includes both neutral white and warm white variations because, as we have seen from the above spectra, the color temperature changes with the time of day (and for example, with the weather, but let’s leave that aside for now), so in reality, we would need a continuously changing color temperature light source that adapts to the time of day and our activities while being eye-friendly. In the absence of this, we currently have to be satisfied with two fixed but eye-friendly color temperatures.
A neutral white LED is recommended by the manufacturer for work or any other active activity. These LEDs also have a suppressed blue light component, making them “less tiring for the eyes compared to traditional neutral white or cool white LED bulbs. They support cognitive functions for better focus. Great for children’s rooms, study rooms, kitchens, and anywhere that requires high workload, quick responses, learning, and comprehension. Reducing the blue and green components positively affects ( although from the above statements I would think the opposite ) the production of serotonin or the happiness hormone, which influences our thinking, creativity, performance, and concentration ability. Lack of it can lead to depression, fatigue, decreased activity, or even vision loss.” – states their brochure. Am I the only one who feels this marketing text needs some polishing? I think it’s better because the higher blue and green values positively influence these factors, while reducing the sharp blue spike and raising the turquoise-green trough provides a more balanced dose, which is more natural.
The manufacturer recommends the use of warm white for better sleep. “After warm white lighting, you will sleep better. The TRUE LIGHT LED bulb’s warm white light (2700K) is perfect for places where you want to relax and unwind after a tiring day. It is particularly suitable for bedrooms, conservatories, dining rooms, etc. Reduced emission of blue and green components naturally promotes melatonin production, helping you fall asleep easily. If you have trouble falling asleep, we recommend using this light at least ninety minutes before bedtime. The quality and quantity of sleep affect our health and life expectancy.” – that’s roughly the promise.
Overall, the TRUE LIGHT LED light sources minimize blue light emission and help stabilize the human biorhythm. They support the proper production of the sleep hormone melatonin, which helps the body regenerate. These lamps are unique in that they contain special Bridgelux Thrive chips specifically developed for this purpose.
Do you think only “marketed” low blue light LEDs exist?
Low blue light emitting LED lamps have been available for years, but no one advertises them as such, and the manufacturer does not claim that they are. There are two reasons for this.
These are extra warm white, also called amber, and are recommended for vintage interiors. However, there is a certain gold-black modern style trend in which they are also favored.
Basically, they mimic the light of carbon filament Edison bulbs or candlelight.
Overall, they are so yellow-toned that they are more suitable for mood lighting. That is, the same purpose as the warm white version of the TRUE LIGHT LED bulb – for places where you want to relax, slow down, and chat, such as bedrooms, conservatories, dining rooms, etc., but in an even more yellowish tone.
They mostly achieve this tone by actually having 2700 Kelvin LEDs in the lamp, but the bulb is not clear but colored with so-called gold foil, which filters out the cooler shades. This gives a strongly yellow tone.
In rarer cases, such as LED strips, they inherently have 2200 Kelvin chips.
For the 1800 Kelvin ones, the chip itself is warmer white, and the bulb is also gold-foiled.
My Conclusion on Blue Light
- We need all colors because that is natural.
- Light from the sun also arrives in the range from turquoise blue to purple. The turquoise-blue range regulates our circadian rhythm. So, during the day, a lot of blue light hits us, making us active and able to concentrate well on work and other activities. As the sun begins to set, the sun’s rays hit the atmosphere at an increasingly shallow angle, and due to atmospheric refraction, the bluer tones scatter more into space, and warmer tones reach the surface. This is why sunset lighting becomes increasingly yellowish, then reddish. Thus, the proportion of blue in the visible spectrum decreases, which our body interprets as a signal to slow down and prepare for night rest. This wouldn’t be a problem if we woke and slept with the chickens.
- We have evolved to this over millions of years.
- Under natural conditions, we would work more in the summer and less in the winter, naturally outside, in natural light.
- How long is there daylight in winter? I haven’t looked up the exact numbers, but I guess that in our country, in winter, we could consider it to be a maximum of 6 hours, and in summer, perhaps up to 12 hours.
- In contrast, we spend 8-10 hours working every day, winter and summer, plus a few more hours where we need to be active and attentive. This requires the presence of blue light.
- So, we would need 10-14 hours of daylight year-round, based on our current general active lifestyle.
- Today, we mostly carry out our activities indoors, so we also need artificial light for this reason.
- Furthermore, from the above reasoning, it is clear that we are more active (especially in winter) than the amount of natural blue light available to maintain our activity level.
- In the past, we only had traditional bulbs, which lacked blue light. This made it harder to maintain attention. Thus, the blue light content of cool white LEDs seems more like a blessing than a curse, as it tricks our bodies into thinking it’s daytime, allowing us to work more intensely with daytime alertness. This reduces the chance of errors, allows us to stay active longer, and pushes our bodies to the limit – hooray!
- Yes, I also notice the unnatural blue spike in the spectrum of cool white LEDs.
- This is not a normal thing.
- But I understand that this is how classic white LEDs were produced.
- They didn’t want them to be very warm white, so they could only mix an additive into the phosphor mix that resulted in this unpleasant spike.
- But you can see, they are working on flattening the blue to make the spectrum resemble a more natural curve.
- Why does this currently only exist in neutral and warm white? Maybe we can thank the blue-scare marketing for that.
- Who would buy a cool white that resembles the daylight spectrum now? For example, me and quite a few others, but the majority listens to the fear-inducing marketing, so we probably wouldn’t sustain such a production yet.
- If someone decides to
- work in three shifts,
- be a night owl, staying up late naturally,
- or loves programming at night,
- or receives another urgent task via Messenger from their excellent employer just before bed and wants to complete it before sleeping…
Then yes, this is all unhealthy and unnatural. But if we choose to act against our natural biorhythm, isn’t it logical to use lighting that provides blue light to help us work more intensely and with fewer errors? Afterwards, of course, we can’t fall asleep because we’ve overstimulated ourselves before bed. Instead of preparing for bed by using a dimmer light with reduced blue light emission at least an hour before sleep, we go to bed right after finishing work without winding down, causing our minds to keep racing about the task. If you overstimulate yourself at night, you’ll have difficulty falling asleep.
- If you want to live healthily, in tune with your circadian rhythm, you work during the day under stronger lighting that includes blue light, and in the evening, you use dimmer lights with reduced blue light emission and don’t work at night, but slow down. You don’t surf the net, you don’t use your phone, you turn off the wifi, and you don’t watch the next series on TV. Can you handle it? – No.
- If you think just changing your lamp to a blue-light-free one and continuing to work at night will solve everything, then you haven’t understood much from the above.
Is the Decision Yours?
Will you also change your lifestyle, or will you be satisfied by checking off that you have installed reduced blue light emission neutral white (4000 Kelvin or above) lamps in the living room, kitchen, and study, and reduced blue light emission warm white (below 3000 Kelvin) lamps in the bedroom, above the dining table, and other places of tranquility?
I wrote all this while using large blue-spiked cool white LEDs everywhere possible and loving to work at night (because I’m a night owl) on a big blue monitor, next to cool white LED light. – Okay, I get it. Now I’m going to feel a bit ashamed.