If You Can’t See the Flicker, Is It Still There?

New brain imaging research challenges lighting assumptions and gives lighting people more to consider

Lighting people have long treated flicker as a visual issue. If you can’t see it, it’s not a problem. But a new study, published in LEUKOS - The Journal of the Illuminating Engineering Society, offers reason to rethink that assumption. Researchers found that even flicker at 100 Hz — well above the threshold of human perception — still triggered measurable activation in the brain’s visual cortex. At 50 Hz, the response was expectedly strong. At 100 Hz, it was smaller but clearly present.

Cheap Drivers Are Still Failing Basic Flicker Tests

At the low end of the market, flicker isn’t just a neurological question — it’s a visible flaw. Inexpensive LED drivers, especially those in residential-grade tape light kits or low-cost troffers, often use low-frequency PWM dimming (typically 100–400 Hz) without smoothing capacitors or analog controls. The result? Visible shimmer, strobing during motion, and eye strain in real-world applications. Try reading a book under one, or glancing at a spinning fan blade, and the flicker reveals itself immediately.

Spec sheets from these products rarely mention flicker, let alone provide flicker index, waveform, or modulation frequency. The focus is on price, not performance — and users, especially those sensitive to light, pay the price in headaches, fatigue, or worse.

Premium Drivers Do Better — But Not Always Enough

On the premium end of the market, Lutron has long been a go-to brand for reliable, high-performance drivers, especially in applications where smooth, deep dimming and visual comfort matter. Their Hi-Lume LED Driver line, for example, offers dimming down to 0.1% and is marketed as “flicker-free” — a claim backed by years of engineering consistency and real-world performance.

That said, the spec sheets we sampled don’t go deep into flicker-specific metrics. While performance is excellent, details like modulation frequency, waveform shape, or percent flicker aren’t typically published. It’s not a knock on Lutron — they’ve set the bar in many areas — but it does highlight the current gap between what top-tier drivers achieve in practice and what’s documented in terms of biological flicker transparency, especially in light of newer research.