Is LED Lighting Harmful To Health? – The Dark Side Of LED Lighting You Should Know

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Is LED Lighting Harmful To Health - The Dark Side Of LED Lighting You Should Know
Is LED Lighting Harmful To Health? The Dark Side Of LED Lighting Graphic © Background images: Shutterstock #1706799604 (under license)

We think of LED lights as a very recent invention, but Light-emitting diode (LED) technology has in fact been around for over half a century. It was introduced in 1962 by General Electric scientist Nick Holonyak Jr., who named it “the magic one.”

These lights have, since then, gained recognition and customers worldwide. As documented by Statista, LEDs are now very big business. They are worth US$ 86 billion in global market share. [1] This is mainly because they are both energy efficient and have a long lifespan, making them preferable from an environmental standpoint. Relative to old-style filament lighting, more of the energy is converted to light and less is converted to heat. This has made the CFL and incandescent lighting options to be phased out as the LEDs slowly become the standard lighting technology.

However, the side effects of these lights, in regard to the safety and health effect of the light they emit, isn’t a topic that’s discussed often. It’s sad in a way because this seemed in every way to be the “perfect light” – energy efficient, low in toxicity, cheap to produce and long bulb life. So this is a hard pill to swallow for the consumer trying to save a dime on their electricity, the government trying to cut carbon emissions and even the LED industry.

But its dangers have been backed up by study after study, as a Harvard Medical School report puts it. [2] In fact, one physician and professor at Wismar University in Germany, Alexander Wunsch, clearly states that:

“Blue light, isolated from all the other colors on the light spectrum, is damaging our retinas and disrupting our endocrine systems, resulting in all sorts of physical and even mental illness.”

The Difference Between Natural Light And LED Light

Natural light is full of dynamic (the intensity and mix of colors depending on the time of the day) and spectrum (light contains all the colors of the rainbow).

In an interview, Alexander Wunsch explains that natural light gives out these colors in a continuous way. [3] It cycles from soft with a concentration of red in the evenings to bright with blue content during the day. The soft red-rich light signals our body time to relax and enter the sleepy zone, while the bright blue-rich one tells us to be alert and awake.

Regarding infrared radiation— an electromagnetic radiation spectrum region with wavelengths ranging from 700 nanometers to 1 millimeter— Wunsch says that you can feel its heat and warmth. Incandescent light bulbs are examples of lights that generate this radiation. This heat requires more electricity, but it’s worth the extra cost as the red light it gives benefits your health.

The near-infrared is the part found just past the visible red color in the rainbow spectrum. This light has a wavelength of between 700 and 2500 nanometers and is an essential source of energy for humans. It can be generated by fire or candle and helps prime the cells in your retina for repair, regeneration, and rest. However, Wunsch says most people are deficient in it. He also says he uses near-infrared light as therapy for his patients.

When it comes to artificial light sources, most have a static spectrum meaning their mix of colors doesn’t change with the time of the day as seen in natural light. These lights are designed to replicate either evening light (warm light, lower color temperature) or daylight (cool light, higher color temperature).

As for the typical white LEDs, they contain a blue light-emitting phosphor (fluorescent) and diode coating. The phosphor coating converts some blue light into longer wavelengths. This results in a yellowish “looking” light.

Is Led Lighting Harmful To Health?

LEDs lights have caused substantial biological impacts across the world. According to The Guardian, they have altered the behavioral patterns of animals like moths and bats. [4] This is because blue light radiation suppresses melatonin production, a hormone responsible for regulating sleep patterns in animals and humans.

Humans have also been greatly affected since most of their activities require staring at phones, iPads, laptops and other displays backlighted by LED technology. Here are more health problems associated with excess blue light:

Eye damage: Perhaps the most concerning damage by blue light is to the eye. The peer-reviewed journal Molecular Vision published a study where they noted that exposure to blue light with wavelengths ranging between 400-470 nm is responsible for inducing severe damage to the retina. [5] Blue light radiation can also damage the retinal pigment epithelium, which could eventually lead to the death of the photoreceptor cell. [6] And if this happens, total blindness can occur.

Insomnia. This is so significant that many devices now have a “night mode” which eliminates much of the blue light from the display. It is also recommended to stop using the device at least one hour before bedtime – but for many users this is regarded as “not something that is going to happen”. “Orange glasses” are a further option for evening device use as these filter out the blue light.

Blue light after sunset can disrupt our endocrine system. An article published by Harvard Medical School has linked night shifts to heart disease, obesity, diabetes, and several types of cancer, i.e., breast and prostate. [2]

Light suppresses the hormone melatonin, which influences circadian rhythms. This is why blue light causes heart disease, obesity, etc. Dr. Wunsch adds that excessive exposure to blue light creates oxidative stress, damaging proteins, DNA, and lipids. He also says it’s linked to a myriad of pathologies. [6]

The Color Spectrum of LED Lightbulbs and Its Health Effects: Further Studies

Here are some further studies and their findings:

1. Effects of Color on Humans Generated by LED Lighting Systems Research by Córdova-Escobedo et al. (2021) – highlights the importance of color temperature and light color in LED systems for human vision. Adequate lighting contributes to visual health and safety, reducing work accidents. Different colors affect us optically and psychologically, causing sensations like visual fatigue, stress, and even vision impairment. The study emphasizes the need for optimal colors and color temperature in LED lighting systems to support human visual health. [7]

2. Health Risks from Color Perception Under LED Lighting: Kaptsov and Deinego (2017) investigated the risks associated with color perception under LED lighting, particularly in traffic signals. They found that LED lights with wavelengths shorter than 650 nm could lead to inadequate color detection and delayed reactions to signals, increasing the risk of transport accidents. This study underscores the need for careful consideration of LED wavelengths in traffic lights and other signaling devices. [8]

3. Spectrum Effects on Color Visual Performance: Jiang, Lei, and Jin (2014) studied the impact of different light sources, including white and RGB LEDs, on color visual performance under mesopic vision. They found that spectral power distribution (SPD) significantly affects chromatic tasks. White and RGB LEDs were characterized as the most natural and saturating for color appearance. The study suggests that SPD influences color identification accuracy and mesopic color blindness detection. [9]

4. Influence of LED Spectrum on Visual and Nonvisual Effects in Tunnels: Dong et al. (2021) evaluated the biological effects of LED spectrum on human visual and nonvisual responses under mesopic vision in tunnel environments. They proposed using mesopic visual spectral luminous efficiency curves for assessing nonvisual biological effects and blue light hazards. The study recommends using LEDs with high color rendering index (CRI) and correlated color temperature (CCT) in specific environments like tunnel interiors to improve safety while considering the impact on nonvisual photobiology. [10]

5. Appraisal of the Effects on Human Health of Using LEDs: Martinsons et al. (2019) conducted a comprehensive review of the health and environmental effects of LED systems. They confirmed the retinal phototoxicity of acute exposure to blue light and high CCT white light. The study highlighted the long-term contribution of blue light to age-related macular degeneration, suggesting that cold-white LEDs, which emit more blue light, have a stronger impact. The research underlined the need to update exposure limits for blue light, especially for children. [11]

6. CCT Tunable Daylight-Integrated LED Lighting System for Health Improvement: Malik et al. (2023) developed a microcontroller-based LED lighting system that mimics daylight color throughout the day. This system aims to enhance mental health in indoor environments by providing dynamic CCT close to natural daylight. The study supports the idea that natural light has a positive effect on human health and well-being. [12]

Circadian Rhythms In Humans And How They Are Influenced By Light

Circadian rhythms are internal processes that regulate the sleep-wake cycle and repeat roughly every 24 hours. These rhythms are influenced by various factors, with light being one of the most significant external cues.

Influence of Light on Circadian Rhythm and Alertness: XuRan et al. (2014) explored how light exposure influences circadian rhythms and alertness. They found that light affects the timing and amplitude of signals to the brain, impacting circadian rhythms and cognitive functions. The study also discussed the effects of ocular aging on circadian photoreception and the use of electroencephalogram (EEG) to evaluate alertness. [13]

Potential Influence of Light Sources on Human Circadian Rhythms: Sokanský et al. examined the impact of different household light sources on circadian rhythms. They highlighted the importance of choosing light sources with appropriate colors to avoid disturbing circadian rhythms. The study particularly focused on whether LED sources with primary radiation in the blue part of the visual spectrum have a stronger influence on circadian rhythms than classical light sources. [14]

Light Effects on Human Circadian Rhythms: A Review of Recent Andechs Experiments: Wever (1989) reviewed the responses of human free-running rhythms to external stimuli, focusing on the effects of light. The study discussed changes in melatonin secretion and its assumed role in circadian rhythmicity. Preliminary results from experiments with melatonin administration to humans were also presented, offering insights into the interaction between light exposure and hormonal regulation of circadian rhythms. [15]

Phase-shifting Human Circadian Rhythms: Influence of Sleep Timing, Social Contact, and Light Exposure: Duffy et al. (1996) investigated the relative contributions of behavioral events and environmental light-dark cycles to the entrainment of human circadian rhythms. They found that bright light exposure significantly influenced the phase shift of the core temperature rhythm, indicating that light is a crucial synchronizer of the human circadian system. The study suggested that interventions for adjusting circadian rhythms should focus on properly timed light exposure. [16]


The color spectrum of LED lightbulbs significantly impacts human health, affecting both visual and nonvisual systems. Optimal use of LEDs requires balancing color temperature to enhance visual comfort and safety while minimizing negative health effects.

In interview, Wunsch gives tips on how to choose the right bulbs. He says that one should buy LED bulbs with CRI 97, which is closer to that of the sun’s natural light spectrum, which is rated as 100 on the same scale.

For evening use it is now advised to shift to “warm” bulbs and a color balance closer to the red / orange end of the spectrum. This mimics the warmer color temperature of evening sunlight and influences the body’s metabolic processes to begin winding down.

Remember, as crucial as getting the correct bulb is, don’t forget to forgo your caffeine intake past noon, put away your phone an hour before bed, and give yourself the opportunity to sleep.



[1] Statista:

[2] Harvard Medical School:

[3] The Dangers of LED Lighting: An Interview With Dr. Alexander Wunsch:

[4] The Guardian:

[5] Tosini, G., Ferguson, I., & Tsubota, K. (2016). Effects of blue light on the circadian system and eye physiology. Molecular vision, 22, 61:

[6] Schieber, M., & Chandel, N. S. (2014). ROS function in redox signaling and oxidative stress. Current biology, 24(10), R453-R462:

[7] “Effects of color in humans generated by led lighting systems” (2021) –

[8] “Health risks occurring when color is percepted under led lighting” (2014) –

[9] “Research of spectrum effects on color visual performance at mesopic condition” –

[10] “Study on the Influence of LED Spectrum on the Visual and Nonvisual Effects in the Interior Zone of Tunnels” (2021) –

[11] “An appraisal of the effects on human health and the environment of using light-emitting diodes” (2019) –

[12] “A CCT Tunable Daylight-Integrated LED Lighting System for the Improvement of Health and Well-Being of Human Beings” –

[13] “Influence of light on circadian rhythm and alertness” (2014) –;JSESSIONID=403f8be4-6ffa-495c-acd8-594a69e048af

[14] “Potential Influence of Light Sources on Human Circadian Rhythms” (2016) –

[15] “Light Effects on Human Circadian Rhythms: A Review of Recent Andechs Experiments” (1989) –

[16] “Phase-shifting human circadian rhythms: influence of sleep timing, social contact and light exposure” (1996) –

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