These migraine-inducing GIFs will show you which LEDs to avoid

The transition to LED lights, while beneficial for the environment and energy efficiency, has introduced an unintended side effect: flicker. Many people, particularly during the holiday season, experience discomforts such as headaches, eye strain, and nausea when exposed to certain LED lights, especially holiday lights. This phenomenon is largely due to how LED electronics control light output. To dim or regulate LEDs, they are rapidly turned on and off. While the human eye might perceive this as a consistent dimmed light, the rapid oscillation can be disturbing to some individuals. Naomi Miller, a lighting scientist at the Pacific Northwest National Laboratory and an expert in LED flicker, explains that the electronics within LED lights dictate the frequency of this on-off cycle. For instance, when an LED is dimmed to 50%, it might be on for half the time and off for the other half. Although LED technology has advanced significantly, and many modern LED products incorporate better quality electronics to mitigate flicker, the problem persists, especially in cheaper or older models. The U.S. government's push for more efficient lighting, culminating in the ban of most incandescent bulbs, has made LEDs the dominant lighting option, highlighting the importance of addressing flicker issues. Flicker manifests in three primary forms. The first is direct flicker, or low-frequency flicker, which occurs when the light modulates between 3 and 80 times per second (Hertz). This type of flicker is directly observable and can be particularly problematic, potentially triggering adverse reactions in individuals susceptible to photosensitive epilepsy. Miller emphasizes the importance of avoiding such low-frequency lighting in indoor environments. The second form is the stroboscopic effect, which becomes apparent when an observer maintains a fixed gaze but something in the light's vicinity is in motion. This effect, occurring with lights oscillating between 80 and 2000 Hertz, makes moving objects appear jerky or unevenly blurred. An example is waving a finger in front of a flickering LED light, where instead of a smooth motion, distinct, frozen images of the finger appear. This can be identified by recording the light with a phone’s slow-motion setting, revealing the rapid strobing. Finally, the 'phantom array effect' or 'ghosting effect' occurs when the eyes move relative to a flickering light source. This creates the illusion of a repeating pattern, like a 'zipper' or a 'string of lights,' as the light's image is spatially displaced on the retina during eye movement. This is often noticeable when driving at night, observing the tail lights of other vehicles, where a single tail light might appear as a series of lights, making it difficult to ascertain the actual position of the moving car. To minimize flicker, Miller advises against purchasing the cheapest bulbs, testing lights using a finger or a phone's slow-motion camera, and returning unsatisfactory products to manufacturers to signal consumer dissatisfaction. #LEDLights #LightFlicker #HolidayLights #LightingTechnology #EyeStrain #Headaches #EnergyEfficiency #StroboscopicEffect #PhantomArrayEffect