Lack of context: While some people prone to migraines have reported being able to detect flickering in LEDs and experiencing migraine symptoms, there is no evidence that this affects the vast majority of people.
FULL CLAIM: “[LEDs] will actually start to cause headaches and migraines and all types of pressure to build up in the brain, so that you’ll start to get frustrated and develop anxiety”; “one of the leading eye doctors in the world also talked about how LEDs are the major cause of cataracts”
REVIEW
Light-emitting diodes (LEDs) are a compact, low-energy technology for producing light. Because of these properties, they are widely used in display screens and increasingly in room lighting.
In September 2024, a widely-shared Facebook reel made a number of claims about the safety of LEDs. The reel featured Matt Roeske, owner of a supplements company, who previously made several inaccurate or unsupported claims that were reviewed by Science Feedback, including the claim that viruses don’t exist.
As this review will explain, Roeske’s claims about LEDs are also not supported by evidence.
Flickering of LEDs doesn’t affect most people
In the reel, Roeke mentioned how LEDs work by flickering on and off. This is known as temporal light modulation and is a consequence of the electrical supply for bulbs. Alternating current operates at a frequency of 50 Hz in most of the world and 60 Hz in North America. This means that the lights effectively turn on and off at least 100 times per second[1].
Roeke claimed that the flicker of LEDs “will actually start to cause headaches and migraines and all types of pressure to build up in the brain, so that you’ll start to get frustrated and develop anxiety”. A report by the EU’s Scientific Committee on Health, Environmental and Emerging Risks found that while there are anecdotal reports of migraine sufferers noticing LED flickering and potentially bringing on symptoms, this only seems to affect a small proportion of people. Roeke’s claim that LEDs “will” cause migraines and anxiety implies that this is a widespread phenomenon affecting large numbers of people, which is not supported by evidence. There does not appear to be any large-scale studies that have precisely quantified how many people are actually affected by flickering from LEDs.
The perception of flickering by people with migraines is a known concern in the industry. While there are LED systems that can avoid or reduce flickering, there is a lot of variation[1]. There are efforts to reduce the impact of flickering, including regulations introduced in the EU. However, one of the challenges is the difficulty in developing a standardized way of measuring the degree of flickering[2].
No reliable evidence of LED light causing cataracts
In the reel, Roeske claimed that “one of the leading eye doctors in the world also talked about how LEDs are the major cause of cataracts”. It’s not clear which doctor he was referring to, but there is little to no evidence of a link between LEDs and cataracts.
Cataracts are when the lens of the eye becomes cloudy, reducing the quality of sight. LEDs are certainly not the leading cause of cataracts. The biggest reason is age; the prevalence increases from 3.9% between the ages of 55 and 64 to 92.6% for people aged 80 and older. The U.S. National Eye Institute also lists several other risk factors, including diabetes, smoking, alcohol abuse, family history, and excessive sun exposure. The list doesn’t include LEDs.
The risk from sun exposure is due to the high levels of UV light, which is known to increase the likelihood of cataracts developing[3]. UV light carries a lot of energy, which can cause damage to the body in a variety of ways. LEDs used for room lighting and screens do not emit UV. However, they can emit high levels of blue light, depending on the type of bulb used (see Figure 1).
Figure 1 – Light frequency spectrum for cool (5000 K) and warm (2700 K) LED bulbs. UV light is below 400 nm, blue light centers around 450 nm, and red light goes up to 750 nm. The choice of cool or warm LEDs dramatically changes the intensity of the blue light. Source: Archer[4].
There is limited research into the effect of blue light on cataracts. A 2023 review of research into blue light exposure cited two experimental studies that studied cataract formation[5]. Both were published by a group of researchers studying eye lenses extracted from pigs.
In the first study, the lenses were exposed to extremely high levels of blue light for 24 hours, after which they showed signs of cataract development[6]. However, the results showed higher damage caused by blue light than UV light, which contradicted what was known from previous research. The authors could not explain this anomalous result. However, they noted that the lens tissue degenerates after five hours following extraction from the eye, so this may have had an impact on the results.
In the second study, the researchers included a sample that was exposed to red light to act as a comparison[7]. As red light is less energetic than blue light or UV, there is no reason to expect that it would cause cataracts in normal conditions. Although the authors concluded that the blue light caused cataract formation, the results did not show a statistically significant difference between the blue light samples, the red light samples, and unirradiated controls.
According to the research paper, the total blue light exposure of 6 kJ/cm2 was comparable to that used in a study of rats that has since been retracted due to concerns over the data and the conclusions. In the retracted study, rats were exposed to 3000 lux of blue light for 12 hours a day for four weeks. Lux is a measure of light intensity and, for context, a typical office might be 500 lux. This means that in just 24 hours, the pig lenses were exposed to the equivalent of a month’s worth of being in an office in pure blue light that is six times brighter than normal lighting. This extreme scenario makes it impossible to conclude anything about the much lower exposure to blue light that a typical person will experience.
Even if blue light from LEDs did increase the risk of cataracts, it would have a very small effect compared to natural sunlight. As previously mentioned, UV light is a known risk and this is prevalent in sunlight, but not in LEDs. Even looking at blue light alone, the strength of radiation from a clear blue sky would be much stronger than from a screen or bulb.
In conclusion, while the flickering of LEDs may have an effect on people prone to migraines, there’s no evidence that it has an impact on the vast majority of people. The research into the effects of blue light on cataract formation is at a very early stage, using extreme conditions that are not relevant to everyday experiences and the results are not conclusive. There is no clinical evidence that LEDs are a cause of cataracts, never mind Roeske’s claim that they are the “leading cause”.
REFERENCES
- 1 – Miller et al. (2022) Flicker: A review of temporal light modulation stimulus, responses, and measures. Lighting Research & Technology.
- 2 – Dekker et al. (2023) Facility for calibration of photometers for measurement of temporal light modulation. Lighting Research & Technology.
- 3 – Liu et al. (2017) Cataracts. Lancet.
- 4 – Archer (2018) Color temperature of light-emitting diode lighting matters for optimum growth and welfare of broiler chickens. Animal.
- 5 – Cougnard-Gregoire et al. (2023) Blue Light Exposure: Ocular Hazards and Prevention—A Narrative Review. Ophthalmology and Therapy.
- 6 – Haag et al. (2021) Cataract Development by Exposure to Ultraviolet and Blue Visible Light in Porcine Lenses. Medicina.
- 7 – Zeller et al. (2022) Influence of Visible Violet, Blue and Red Light on the Development of Cataract in Porcine Lenses. Medicina.
