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Recent Innovations forced mostly by newer and stricter government regulations have brought us through extremely unreliable CFL light bulbs from the old incandescent light bulbs to these very expensive yet aledged long life LEDs. So far I'm okay with these LEDs especially how cool to the touch they are. But I have been noticing a high frequency flash involved. One can see the flash by using a fidget spinner and observing the light and area it illuminates. Is this something we should be be thinking about as far as health issues may be concerned?

Jon Newsom
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  • Probably not but it plays merry hell with my infra-red remote controls. –  Sep 11 '17 at 22:13
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    If you're noticing a flashing, chances are it's not *that* high of a frequency, maybe 100-120Hz depending on your locale. – W5VO Sep 11 '17 at 22:17
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    Really @BrianDrummond? I had not heard that. – Trevor_G Sep 11 '17 at 22:24
  • Maybe just one brand of LED bulb, it must switch somewhere close to 38kHz. –  Sep 11 '17 at 22:36
  • Related: https://electronics.stackexchange.com/questions/79373/how-to-choose-right-pwm-frequency-for-led – Dampmaskin Sep 11 '17 at 22:56
  • I've used CFLs for a long time and have not found them unreliable. – Robert Endl Sep 11 '17 at 23:01
  • @RobertEndl CFLs die very quickly (my experience) when used in outdoor lamp settings on the front porch, for example. The problem crops up far more frequently during our winters, than summers, so it seems to be related to ambient temperatures. – jonk Sep 11 '17 at 23:19
  • Long lasting CFL and LEDs is utter baloney. Both types have at least one electrolytic capacitor connected after primary AC rectifier. Best electrolytic caps are rated at 5000 hours at best, so when subjected to horrible heat of 80-100C, they should die in ~208 days of continuous running. – Ale..chenski Sep 12 '17 at 00:10
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    @ali that would be a bad bet in deciding a 5 or 10 year warranty – Passerby Sep 12 '17 at 00:54
  • @Passerby, I just replaced one (out of 11) LEDs made by Feit Electric, it became intermittent, after less than 3 years of service in kitchen. I also have three CREE-brand "100-W" bulbs that have a gradual decay - the bulbs are made of 20 LEDs, and 60-70% of LED chips have failed. Go figure. – Ale..chenski Sep 12 '17 at 01:12
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    Feit is cheap. Cree comes with 5 year if I recall. You have your receipt right, get a warranty exchange – Passerby Sep 12 '17 at 05:29
  • I don't use CFLs out of doors so I don't know about that. However I do light maintenance at my condo association which includes changing light bulbs. CFLs have shown very good reliability. Also, I stopped using tungsten lamps in the exit lights and am now using LEDs. Haven’t had one failure yet. – Robert Endl Sep 12 '17 at 23:55
  • I started replacing the incandescent bulbs with CFLs well over a decade ago in my mother's house inside and out. I found after a year or so that most of the bulbs I changed are CFLs. They weren't lasting a year in most cases where the old bulbs were being changed between three and five years, some much longer. I've had it with CFLs. I've started replacing them with LEDs. Believe it or not I've still got some with the tungsten elements but when they go I'll plug in LEDs if that is still the desirable technology of the day. – Jon Newsom Sep 14 '17 at 13:02
  • I nominate this question for "wierdest question" of the year. All that aside, I write the date of installation on LED bulbs base to keep the manufacturers honest. – Voltage Spike Sep 21 '17 at 15:39

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Continuous exposure to flickering light is known to cause myopia in developing eyes (here's a clinical study in guinea pigs, albeit with the frequency 2 orders of magnitude lower than you'd expect in LED lights). It was also the primary reason for CRTs to have ever-increasing refresh rate, which is close to the flickering frequency of LED lights. Apparently, the damage is reduced as the frequency increases, at least I can certainly assert that I've spent more than 4 weeks in front of a CRT as a kid, and I didn't get myopia yet.

Note that flickering is only present in the cheapest devices which lack any smoothing or regulation circuit, so if your LED lights have noticeable flickering, just go for a better brand. Those will have LEDs driven either constantly, or at much higher frequency.

Dmitry Grigoryev
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LED driver circuitry can involve switching the diode ON and OFF over time, but it is not a requirement for LEDs in order to work. Higher end lamps will probably tend to switch in unnoticeable frequencies or maintain the diode ON all the time. Eyes on the other hand depend on chemical reactions to sense light, these reactions take a little while to happen so your body can't tell the difference between a brighter flashing light and a dimmer steady-ON light if frequency is high enough. There are no proven detrimental effects of high frequency flashing lights in our physiology. Experiments to test these ideas are simple and have been conducted. PubMed is a well known journal where you can search for articles regarding the subject!

Juan Manuel López Manzano
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I'm sure someone will swear they cause migraines or worse.. But whatever health issues they may just represent has to be better than all the mercury in the CFLs.

Any flashing you may see though is more a characteristic of how the LEDs are driven, not the LED's themselves.

Trevor_G
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  • There are many makers of LED bulbs. I believe the cheapest way to control the average current across the LED is PWM. And no one knows which control frequency they would choose to get their bulb running until a user forget where he put sales receipts to claim the warranty. So very likely there are LED bulbs that flick like hell. – Ale..chenski Sep 12 '17 at 00:15
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    Mercury in the CFLs has zero impact of health, unless the OP keeps smashing light bulbs in his house. – Dmitry Grigoryev Sep 12 '17 at 12:06
  • @DmitryGrigoryev yes I was more thinking about the proper disposal issues. Around here, you are supposed to take them to the waste disposal station to be properly handled, but I seriously doubt anyone does even if they are aware of it. SO instead the Mg is being added to the landfill / environment. – Trevor_G Sep 12 '17 at 13:57