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The Irish Independent details the claims of a woman saying she is sensitive to LED light, and that it causes her nausea.

The article explains that neurologists, opticians and ophthalmologists found nothing medically wrong with her. That still leaves psychosomatic effects.

Is there any scientific evidence of people being sensitive to light specifically from LEDs, beyond psychosomatic symptoms?

Oddthinking
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Mikey Mouse
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    Well, incandescent and LED lights do have different spectral properties (see for instance http://physics.stackexchange.com/questions/108783/why-can-colors-be-mixed ). – nico Apr 23 '15 at 13:40
  • @nico Yeah, I'd be surprised if they were identical, but I'd also be surprised if there was a property beyond brightness and colour/wavelength that a human could reliably identify and have such an extreme reaction to. – Mikey Mouse Apr 23 '15 at 14:44
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    I've edited greatly, but I am still uncomfortable with the question's handling on psychosomatic cases. Someone with psychosomatic nausea, for example, is still nauseous and still has a medical condition, even if there are no physical causes. If, as it appears, this is a psychosomatic illness, we need to be careful neither to blame the manufacturers, nor the sufferer. – Oddthinking Apr 24 '15 at 12:16
  • @Oddthinking Cool, thanks for the edit – Mikey Mouse Apr 24 '15 at 12:41
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    Besides the spectral differences, it's also worth noting that many LED lights actually flicker. It takes much less energy and is less damaging to the LED to produce a series of very bright pulses than to keep it continuously lit, and human vision can't tell the difference due to persistence of vision and our general speed of processing. Dimmable LEDs often achieve the dimming effect by varying the pulse spacing, rather than the brightness. It's been noted that flourescent tube lights (which also flicker, albeit at a slower rate than LEDs) can cause headaches. Perhaps it's similar? – anaximander Apr 24 '15 at 14:43
  • Can she watch TV, most of which are now LED? As are vehicle head lamps, and all smartphones. Hope this isn't a real condition! – geoO Apr 02 '19 at 18:05
  • The question still leaves open the possibility that, even if an effect is real, it has nothing to do with the light *source* but more do do with issues unrelated to the source such as flicker, which is a property of the electronic divers of the source and which can vary independently (badly driven fluorescent tubes cause some issues for people, but well-driven ones don't). – matt_black Apr 24 '22 at 11:27

1 Answers1

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Yes, it is recognised as a potential problem: LED lighting flicker and potential health concerns: IEEE standard PAR1789 update.

The IEEE Standards Working Group, IEEE PAR1789 “Recommending practices for modulating current in High Brightness LEDs for mitigating health risks to viewers” has been formed to advise the lighting industry, ANSI/NEMA, IEC, EnergyStar and other standards groups about the emerging concern of flicker in LED lighting. This paper introduces power electronic designers for LED lighting to health concerns relating to flicker, demonstrates that existing technologies in LED lighting sometimes provide flicker at frequencies that may induce biological human response, and discusses a few methods to consider when trying to mitigate unintentional biological effects of LED lighting.

The physiological pathway is that all humans are sensitive to flickering light - the range of sensitivity in both frequency and intensity varies by individual. At normal mains frequencies (50 or 60Hz) the vast majority of the population is insensitive but some people are.

This 2011 (unpeer-reviewed?) article, Exploring flicker in Solid‐State Lighting:   What you might find, and how to deal with it discusses it further, showing the different sorts of flickering that occurs from different types of light sources, plus a brief summary (with references) of some of the health effects flickering can cause, including this excerpted list:

  • Headaches and eyestrain
  • Neurological problems including photosensitive epilepsy
  • Reductions in visual performance
  • Distraction
  • Disruptive behaviors in individuals with autism
Glorfindel
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Dale M
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  • Wow, interesting find. You prompted me to do more research, and I've expanded your answer with it. Please check you are happy with it. – Oddthinking Apr 30 '15 at 00:51
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    (I wouldn't say this is definitive evidence that LEDs, in particular, do cause the symptoms described, but I think it demonstrates that, to my great surprise, it is physiologically/physically *plausible* that LED light could directly cause nausea.) – Oddthinking Apr 30 '15 at 00:54
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    Should point out that flicker is neither inherent to LEDs, nor limited to them. It comes from the 60 Hz frequency of the power grid (50 Hz in Europe, IIRC), so it would, for instance, be quite simple to add capacitance to the LED driver circuit to eliminate this. Or test the sensitive person with LEDs driven by both A/C and D/C. – jamesqf Apr 30 '15 at 06:30
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    LEDs are not powered directly from power grid. There is a power supply integrated into "lightbulb" that lowers the voltage. This power supply uses [PWM](http://en.wikipedia.org/wiki/Pulse-width_modulation) circuit, which boosts flickering frequency to very high values (tens of kHz) as a side effect. – n0rd May 01 '15 at 00:52
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    @n0rd The PWM circuits in LED light bulbs *can* boost the frequency into the kHz range, but cheap versions might not do so. Another thought: LED bulbs that use PWM would have to be dimmable bulbs; if they were non-dimmable it would be cheaper to use a resister than a PWM chip to control the bulb's brightness. – Mar Sep 04 '15 at 23:06
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    The power supply in an led light is called a *driver*, though sometimes people call it a ballast, which is what the power supply for a fluorescent light is called. Just FYI if someone wants to know the right terms to search for additional research. –  Mar 29 '19 at 17:30
  • One thing that has not been clarified in news stories is whether anyone has done experiments on LEDs using *different* type of driver (eg cheap low frequency ones with mains frequency flicker versus better ones where the frequency is much higher). This seems important given the mechanism and might lead to a conclusion that the problem is how the LED is driven and not the fact that it is an LED. – matt_black Aug 26 '19 at 11:48
  • @n0rd, cheap LED lights *are* powered directly from the grid. An LED is a diode, so a string of them in series connected to mains power will light up 50 or 60 times per second. – Mark Aug 26 '19 at 23:55
  • @Mark no - put mains voltage over a diode and you get slag. – Dale M Aug 27 '19 at 00:05
  • @DaleM, that's why you use a *string* of diodes. At a rough estimate, put US mains voltage over 40 white LEDs in series, and you'll get white light, not slag. – Mark Aug 27 '19 at 00:25