Flicker is variation in light output over time, usually from driver or dimming behaviour. Even flicker invisible to the eye can contribute to headaches and eye strain over long exposure.
Spaces with extended occupancy — classrooms, labs — call for flicker-free drivers to protect comfort during long sessions.
The Science
LEDs have none of the thermal inertia an incandescent filament has, so their output can follow current changes in nanoseconds — any ripple in the driver's output shows up directly as flicker. Cheap drivers don't fully smooth the ripple from AC mains, which crosses zero voltage twice every cycle. Percent Flicker is a common spec but it ignores frequency entirely — a light pulsing 100% at a highly visible 5Hz scores identical to one pulsing 100% at an imperceptible 30,000Hz. Pst LM and SVM are better because they weight results against how sensitive the eye-brain system actually is, from 0.3Hz to 80Hz over a 10-minute window.
Visible flicker below about 70Hz can trigger photosensitive seizures in susceptible people. Even flicker in the 80–200Hz range that nobody consciously notices can still overstimulate retinal pathways and contribute to migraines, tension headaches, and eye strain, and flicker around moving machinery can create dangerous stroboscopic illusions.
Subconscious processing of erratic light patterns measurably impairs short-term memory and reading comprehension, and chronic exposure raises irritability and error rates in task-heavy environments.
See this parameter in action, across every stage and environment, in the full interactive simulator.
Open the full live simulator →Discussion
0 comments on this guide.
No comments yet — start the discussion.
