Effects of invisible flicker in your LEDs

flicker in LEDs

With the ever-increasing penetration of LED (light emitting diode) lighting in our homes, offices, schools and almost everywhere in our lives, one might expect that this new energy-saving technology should be good for health too especially our eyes.

In India, increasing adoption of LED lighting is being witnessed across residential and commercial sectors, government projects and more. As a result, the future of LED market in India is bright. In value terms, the Indian LED lighting market is projected to grow at a CAGR of 24.66% during 2016-2022, to reach $ 3,758.74 million by 2022. However, recent research reports and investigations show that most of the LED lighting products available in the market may exhibit anomaly high flicker not visible to naked eyes. Due to this, LED lighting is of concern in domestic and other non-industrial environments where awareness is likely to be low. Several lighting brands are cutting corners to push sub-standard LED products into the market, which may cause health concerns. 

According to PAR1789 of IEEE, flicker from electric light whether visible or invisible flicker, for some populations can be a trigger for headaches, migraines, fatigue, epilepsy, and other neurological responses. Flicker has been shown to degrade reading performance, provide a distraction or annoyance for sensitive individuals (including subtle changes in behavior in vulnerable groups). 

Dr. Jatin Ashar, Ophthalmologist, Mumbai Eye Care Cornea, and Lasik Centre, says    “non-visible flicker can be the cause of an entire array of performance and health effects, ranging from eyestrain to serious neurological problems. Often, office goers complain about headaches and dizziness. The culprit could be flickering LED lights at your workplace and unfortunately, turning them off isn’t an option if you work for hours. To protect your eyes from this harmful exposure, take regular breaks during the work hours. If possible, ask your co-workers to join you in requesting healthier lighting choices (with flicker rate not more than 30%). Also doing simple eye exercises and getting regular eye check-ups done can go a long way in preserving the health of your eyes”.

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The potential health effects of flicker can be divided into those that may immediately result from a few seconds’ exposures, such as the risk for epileptic seizures, and those that may be the less obvious result of long-term exposure, such as malaise, headaches, and impaired visual performance. The former is associated with visible flicker, typically within the range of ~3 to ~70 Hz; and the latter, with invisible modulation of light at frequencies above those at which flicker is visible (invisible flicker). Human biological effects of flicker are a function of the flicker characteristics (principally frequency and modulation depth), the characteristics of the stimulus (luminance, spectrum, size, contrast), characteristics of the individual (adaptation state of the eye, individual differences in sensitivity), and several other factors.

California State in the United States of America has defined the standards. According to its Title 24, it requires high efficacy LED sources to be ‘low flicker operation’, implying that the LED product at frequencies below 200Hz will have less than 30% flicker. Title 20 also requires ‘low flicker operation’ of LED lamps. Unfortunately, there are no standards in India and most LEDs have flicker rate of anything between 40% to 80% much higher than the California benchmarks.

Interestingly, it is not very difficult to detect an invisible flicker in your home LEDs. One of the simple and effective methods for consumers to detect light flicker in LEDs is through your mobile phone camera in the slow motion mode. By simply targeting the LED lamp and looking it in the mobile screen in the slow-motion mode, one can determine the flicker in LEDs. 

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So next time when you feel strain in your eyes, headaches and similar symptoms, do check your LEDs! 


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