Transcript
If you get headaches, migraines, eye strain, or are autistic, your lights could be making things way worse without you realizing. Here's how to tell. Right now, this room is literally pitch-placked for 30% of the time. It's like I'm out of rave, but my brain doesn't see it. Don't believe me? Let's slow it down. This is the same lighting, but at slower speed. This is called flicker. I hardly know her. Here's why it happens. Our electricity uses alternating current at 60 hertz, meaning the voltage goes up and down 60 times per second in the U.S. E.Ds produce light when they get a positive voltage. Most use a few tricks to flip it and make the current go from this to this, but that still produces flicker at 120 hertz. We can't visibly detect anything above 60 to 80 hertz, so everything might look normal, letting cheap companies get away with it. But our optic nerve and cortex can still sense it up to around 200 hertz. And it causes problems! A landmark study of office workers in old fluorescent lighting found that when they shifted it from 100 hertz to much, much higher frequency, it cut Any flicker suitably fast is indistinguishable from continuous. This is rarely a problem for old incandescent bulbs because even though the electricity was going up and down, the filament of the bulb heated up and that heat didn't dissipate that quickly. So they would dim 5 to 15% between pulses, which we call modulation depth. And the faster the flicker, the deeper that can go without causing problems. 100% depth is only safe above 1250 hertz. At 120 hertz, it needs to be less than 10% depth. So, to make them safe, they need what's called a driver to convert that alternating current into direct current. That's the power brick between the outlet and the LEDs. But some brands are better than others. This says DC, but it still flickers. Also, when you dim LEDs by some percentage, the cheaper ones will do it by flickering those LEDs on and off for that percentage of the time. Sometimes at dangerously low frequencies. Same goes with dimmer switches. So, the best way for you to identify the culprits is to take a slow-mo video using a the highest FPS your phone can handle. For iPhones, that's usually 240 FPS at 720p. Look for the visible pulsing. I put other methods, apps, devices, and a lot more info in my free Flickr guide that I've been working on all week. Go here and I'll send it to you.
Additional notes
This is a BIG REASON why not all green lights are good for headaches / migraines (if you've been following along on my migraine series, you'll know why green light can help with them). If you get the RIGHT wavelength but it has either natural flicker or flicker when dimmed, you may hurt more than help! A complete 2015 IEEE review linked lighting flicker to: - Photoepilepsy or flashing-light induced seizure. - Stroboscopic effect and associated apparent slowing or stoppage of rotating machinery. - Migraine or severe paroxysmal headache often associated with nausea and visual disturbances. - Increased repetitive behavior among persons with autism. - Asthenopia, including eyestrain, fatigue, blurred vision, conventional headache, and decreased performance on sight-related tasks. #tiktokencyclopediacontest #science #learnontiktok #headaches
References
- 2015 IEEE review on lighting flicker mentioned in caption; title, DOI/PMID, and source link not listed in workbook.
- Landmark office-worker flicker-frequency study mentioned in transcript; title, DOI/PMID, and source link not listed in workbook.