Naked Science Forum
General Science => General Science => Topic started by: thedoc on 24/07/2012 06:30:02
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Pam Martin asked the Naked Scientists:
I listened to your broadcast (http://www.thenakedscientists.com/HTML/podcasts/) on Friday 3rd Feb and I cant wait to hear Chris' comments regarding the topic of light sensitivity.
The lady who phoned in with this condition sounds like she has it very severely. The reason I'm so interested is that I too suffer from the condition, though not quite as badly.
The worst part of this disability is that other people just dont understand or even believe me. I am retired now but during my working years, I was always climbing on desks after hours to switch off overhead fluorescent light bulbs in the hope that no one would notice the next day and then getting into trouble with management and my colleagues when they did. I tried to tell them that the light blinded me and prevented me from seeing what I was doing, but they used to look at me as though I was crazy. To some extent, I don't blame them, as THEY were perfectly comfortable in the very same environment which I found intollerable and they simply could not comprehend what I was experiencing. Most of the optitions I consulted over the years seemed to have very little knowledge or interest in my condition either.
I would therefore love to hear what The Naked Scientist has found out about the subject and furthermore, if it is at all possible, I would realy like to get in touch with fellow sufferers and maybe form a support group of some sort. If anyone would like to contact me, please feel free to give them my email or contact numbers.
Thanks very much for a fascinating programme (http://www.thenakedscientists.com/HTML/podcasts/).
Regards,
Pam
What do you think?
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Some systemic diseases are made worse when the skin of the sufferer is exposed to UV light, e.g. Lupus, Prophyria.
Fluorescent lighting does emit UV, but there is some debate as to whether it is of sufficiently quantity to cause these syndromes to flare-up ...
http://www.lupus.org/webmodules/webarticlesnet/templates/new_magazineback.aspx?articleid=884&zoneid=67
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Perhaps the problem is associated more with flicker than UV. I find the 100 Hz or 120 Hz flicker from traditional mains frequency ballast lighting quite disturbing, but CFLs with high frequency electronic electronic ballasts don't bother me at all.
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I am also more sensitive to flickering lights than most people around me.
Incandescent lights don't bother me, as the thermal inertia of the filament effectively eliminates flicker. However, our area uses tones superimposed on the 50Hz mains to control off-peak loads, and this can upset dimmers, and make incandescent globes flicker in a way that I find most annoying.
Sometimes the long fluorescent tubes bother me when they get old and start flickering.
The CFLs have not bothered me once they start up. However, they are not really intended to be used with dimmers, and this could make them act erratically.
The new domestic LED lights run off DC (and so don't flicker) - but they are also capable of being used as an internet hotspot in the visual spectrum. The standards have been drafted to ensure they don't cause visible flicker, but I guess we'll see when they arrive. Flicker is a very subjective thing.
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The CFLs have not bothered me once they start up. However, they are not really intended to be used with dimmers, and this could make them act erratically.
I was wondering if the problem was with Fluorescent Lamps, and not Compact Fluorescent Lamps.
Cold Cathode Fluorescent Lamps (CCFL) are generally dimmable.
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I was wondering if the problem was with Fluorescent Lamps, and not Compact Fluorescent Lamps.
I had a similar thought. Older straight tube fluorescent lights produce quite a lot of low frequency flicker, not unlike a strobe light. Newer straight tube lights could use a high frequency electronic ballast like the ones used in CFLs, but I'm not sure if they do or not.
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If two high frequency strobes were operating at close, but not the same, frequencies would there be a visual equivalent of the acoustic beats effect (https://en.wikipedia.org/wiki/Beat_%28acoustics%29) ?
The light is not coherent (https://en.wikipedia.org/wiki/Coherence_%28physics%29) so wouldn't cancel out destructively (https://en.wikipedia.org/wiki/Destructive_interference#Mechanism), but I think the combined brightness from two high-frequency sources could still pulsate at a low frequency, (aka flicker), if the lamp frequencies were close.