>It doesn’t make any sense in 2026 that Gmail doesn’t have a dark mode

I've been using dark mode on gmail for years, not sure what OP is talking about here.

But also, my sleep quality got much better when I turned on f.lux. And it got better still when I added a second light to my bathroom that can do a 1800K super-warm light (that's also very dim).

And as an added pro-tip, I use f.lux during the day to cut my color temp to 5900K (instead of the default 6500K) and it made a huge difference for how long I could work without getting tired eyes.