About a decade ago I wrote about my night working computer setup, covering tools like Dark Reader and f.lux. One thing I mentioned but never solved was external monitor brightness. I had resigned myself to fumbling through physical buttons and monitor menus whenever I wanted to dim my screens at night…
It turns out there's been a solution this whole time: most external monitors support a protocol called DDC/CI that lets software control hardware brightness over the display cable.
MonitorControl
MonitorControl is a free, open-source Mac app that uses DDC/CI to let you control external monitor brightness. I installed it via Homebrew (brew install --cask monitorcontrol) and it immediately detected both my monitors. The difference is remarkable. Now I can change the brightness of the display that has the mouse cursor using the standard brightness controls.
Tools I still use
I still regularly Dark Reader. It is still a nice way to shift to dark color palettes. Many sites now either seem to automatically switch colors or have color scheme support, so Dark Reader is less necessary than it was in 2016.
I use a slightly different new tab extension now: Empty New Tab Page.
Tools I no longer use
In the old post I recommended f.lux for turning screen colors warmer at night. macOS now has this built in as Night Shift.
I've also think that while the blue light / melatonin mechanism is real, the practical impact from typical screen use seems smaller than the mid-2010s hype implied. Simply dimming your screens may matter more than shifting color temperature - which makes controlling monitor brightness potentially more useful than color shifting for sleep purposes.
I don't really use MuPDF any more since I rarely read PDFs at night at this point.