Jack Richards
Founder, Sundown
Jack builds tools that protect your biology from your technology. He created Sundown after years of researching PWM flicker, temporal dithering, and circadian disruption on modern displays. Previously co-founded the software behind Ra Optics blue light blocking glasses.
Articles by Jack
Flicker-Free Mode for Mac: How Sundown Eliminates PWM Headaches Without Killing Your Brightness
Your MacBook dims its screen by strobing the backlight thousands of times per second. Flicker-free mode stops the strobing and dims through gamma instead. Here's exactly how it works.
Display Dithering on Mac: The Hidden Flicker Source Your Blue Light App Won't Fix
Every Apple Silicon Mac flickers at the pixel level through temporal dithering. It's separate from PWM, invisible to most people, and no blue light app except one addresses it.
Fix Screen Flicker Headaches on MacBook: PWM and Dithering Explained
Your MacBook has two invisible flicker sources causing headaches. PWM backlight dimming and temporal dithering. Here’s what they are, which models are affected, and what actually fixes them.
Night Shift vs f.lux on Mac (2026): Full Comparison
Night Shift caps at 2700K. f.lux goes to 1200K. Neither has flicker-free mode. Here’s the full breakdown — and why serious Mac users are switching to something deeper.
Best Blue Light App for Mac in 2026: Night Shift vs f.lux vs Iris vs Sundown
We tested every Mac blue light filter app against circadian research. Here's what the specs, the science, and 18 months of testing actually show.