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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?

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    Well, incandescent and LED lights do have different spectral properties (see for instance physics.stackexchange.com/questions/108783/… ). – 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
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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
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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 0:54
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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 6:30
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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 circuit, which boosts flickering frequency to very high values (tens of kHz) as a side effect. – n0rd May 1 '15 at 0:52
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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. – Martin Carney Sep 4 '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. – fredsbend Mar 29 at 17:30

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