This is the blog for Sundown, a small Mac app that lives in the menu bar and changes how the screen looks once the evening starts. You give it a schedule with morning, day, evening and night steps, and at sunset it starts moving the display away from the usual 6500 K white toward amber and then red. It can go as far as 500 K, it moves in steps of 100 K, and the brightness comes down at the same time, so the screen you sit in front of at eleven at night is a lot softer than the one you had at noon.
Most people never open more than the one panel. Click the icon in the menu bar and there is a warmth slider, a brightness slider and a row of presets, which is handy if you want to jump to a deep red for reading in bed without waiting for the schedule to get there.
Sundown needs macOS 14 Sonoma or later and runs on both Apple Silicon and Intel Macs. It is made by Jack Richards and sold directly on the site, with a 7-day free trial and then $4.99 a month, $39 a year, or $79 for a lifetime licence. The download is here: Sundown.dmg.
If you want to read around the subject first, The science behind Sundown collects the research the app is built on, and the Blue Light Calculator is a free page you can use in the browser. Questions go to hello@trysundown.com, and new things show up on Instagram at @trysundown.