Updated: Aug 19, 2020
Today’s conversation is all about the damage caused by the largely invisible flicker generated by LED lighting. The computer and TV industries have worked hard to reduce the amount of flicker from monitors, but the lighting sector is a long way behind.
What is flicker?
Flicker is the pulse or intermittent burst of light generated by the LED chip- packets of energy - electrons - are fired across gaps or holes in the light emitting diode. In that process, a flash of light is generated, and generate this flicker phenomenon.
Although it's an almost inevitable consequence of the way the light is produced, flicker can be made worse by incompatible or poor-quality components and connections in any part of the system: the power source itself, the dimmer or switch on the wall, the driver which is transforming the power from alternating to direct current, or the light fitting itself.
Dimming the LED makes this phenomenon worse because you are essentially reducing the number of ‘packets’ of electrons crossing the gap – if you imagine a funnel full of beads, when there are lots of them flowing out together, they appear as a steady stream. When there are fewer of them, you can see the individual elements more clearly.
It's easy to see flicker by simply recording a low-resolution video on your phone. You may be shocked and surprised to see how bad it can be.
We used to think that flicker was only really harmful “if” you could see it. But, thanks to new sensing technologies it turns out, that there are parts of the brain that are being affected flicker levels, way below the 'flicker fusion' threshold - or anything that we have imagined before. These pulses of light trigger activity in the brain, generating a state of vigilance – and in extreme cases, hypersensitivity – particularly problematic for people with autism, ADHD and sensory processing issues.
Because these flickering LED’s sources are pulsing at a similar rate to the speed at which our eyes track across a scene, it also generates instability and confusion in visual processing – the element that was ‘there’ one moment is darker or brighter the next. This has a powerful impact on speed and accuracy in reading - as well as causing eye strain, headaches, blurred vision and muscle spasm. Research has also found that exposure to flicker also increases repetitive behaviour among people with autism.
I hope you can see that flicker is a hidden yet potentially incredibly damaging problem and well worth taking the time to do what you can to fix it
What you can do about it…
1. Team Talk - see how you can reduce the amount of flicker in your home. Identify the spaces/places which count the most - where you need to concentrate, socialise or sleep and focus your time and investment on those.
2. Track down the culprits - Use a mobile phone to take a video of the lights in your home, and you will see that some of them are flickering more than others. Check the different components in the system - from switch to lamp. It could be as simple as changing the bulb.
3. Repair, replace or distance – we know that bright, flickering light in the central vision does the most damage. We also know that dimming the luminaire makes the flicker even worse. So invest in the best-quality luminaries you can find (there are now some flicker-free alternatives on the market) and use a lower-wattage lamp rather than dimming in the bedroom or living room for example.