Jack Richards
Founder, Sundown
Jack builds tools that protect your biology from your technology. He created Sundown after spending years researching PWM flicker, temporal dithering, and circadian disruption on modern displays.
Articles by Jack
Best Circadian Health Apps in 2026: 9 Tools That Actually Work
The 9 best apps for circadian rhythm health in 2026 — across display filters, sleep trackers, light therapy, and chronobiology. Tested against the research that defines what moves the needle.
Best Screen Dimmer Apps for Mac in 2026: 6 Tools Compared
Need to dim your Mac screen below minimum brightness? We tested 6 dimmer apps — Sundown, MonitorControl, Lunar, BetterDisplay, NightOwl, and built-in controls — on flicker, eye comfort, and actual dimming depth.
How to Reduce Eye Strain on Mac: 7 Fixes That Actually Work (2026)
Most Mac eye strain advice makes the problem worse. Dimming your screen increases invisible flicker and Night Shift leaves 60% of blue light untouched. Here are 7 science-backed fixes that target the real causes.
Blue Light Filter for MacBook: Beyond Night Shift (2026 Guide)
Night Shift blocks 40% of blue light on your MacBook. Here's how to reach 97% and what actually worked after testing every option.
Best Mac Display Health App 2026: Complete Guide
We tested every Mac display health app across four pillars: blue light, flicker, dithering, and scheduling. Here's the full breakdown.
Night Shift Alternative for Mac: Why Apple's Built-In Filter Isn't Enough (2026)
Looking for a Night Shift alternative for Mac? Apple caps at 2700K and blocks 40%. Sundown reaches 500K and blocks 97%.
Sundown vs Iris for Mac (2026): What Happened to Iris and What to Use Now
Iris pioneered PWM flicker protection and deep blue light filtering on Mac. Then it stopped updating in November 2022. Here's how Sundown compares — and what former Iris users should know.
Sundown vs f.lux for Mac (2026): The Honest Comparison
f.lux blocks 70% of blue light at 1200K. Sundown blocks 97% at 500K. Both filter your Mac screen after dark — but the gap between them changes everything.
Mac Blue Light Filter: 3 Methods That Actually Work (2026 Guide)
Your Mac has 3 blue light filter options: Night Shift (20% blocked), f.lux (70%), and Sundown (97%). Here's how to set up each one step by step — and which one circadian researchers actually recommend.
Blue Light and Sleep: What Your Mac Display Does to You
Your Mac emits blue light that suppresses melatonin and disrupts sleep. Night Shift helps, but it's not enough. Here's what actually works.
How to Make Mac Night Mode Darker — Beyond Dark Mode
Your Mac has three levels of darkness and most people only use one. Here's how to go beyond Dark Mode and Night Shift to actual circadian protection at 500K.
Red Screen Filter for Mac — Deep Red at 500K | Sundown
Most Mac 'red screen filters' stop at amber. Here's why color temperature matters, what the science says about 500K vs 2700K, and how to set up genuine circadian protection tonight.
Best f.lux Alternative for Mac in 2026: 6 Options Compared
f.lux pioneered screen tinting in 2009 but hasn't shipped a major update since 2021. Here are six alternatives compared on filtering depth, PWM protection, dithering, privacy, and price.
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.
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.
How to Reduce Blue Light on MacBook Pro: Every Method from 20%% to 97%%
Most guides stop at Night Shift. This one covers every method to reduce blue light on your MacBook Pro — built-in settings, third-party apps, physical filters, and ambient lighting — with the science behind why depth of filtering matters more than you think.
Fix Screen Flicker Headaches on MacBook (2026 Guide)
MacBook screen flicker headaches come from two invisible sources: PWM backlight dimming at 14.8 kHz and temporal dithering on Apple Silicon. Here’s what causes them and the only Mac app that fixes both.
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 CircadianShield vs Sundown
We tested every Mac blue light filter app — including CircadianShield — against circadian research. Here's what the specs, the science, and 18 months of testing actually show.