My eyes have been terrible since grade 4, so I use a lot of "dark mode" apps, to try and avoid squinting at my laptop so much.
But for some reason, it didn't occur to me until now to see if you can do dark mode on … PDFs.
You can! Of course. I'm super late to this party — people have been posting about this for a long time now — but just in case you're as slow as I, here are instructions on how to turn it on in Adobe's Acrobat Reader, via Makeuseof:
Open Adobe Reader and head to Edit > Preferences (using the Ctrl + K shortcut if you wish).
There, choose the Accessibility tab from the left sidebar.
Next, look for the Document Colors Options section. Inside this, check the Replace Document Colors checkbox, then choose to Use High-Contrast colors.
Finally, select the White text on black from the dropdown box next to High-contrast color combination. This theme is easiest on the eyes.
Now, click OK to leave the Preferences window. You should immediately see that any opened PDFs now display in dark mode.
There are also a bunch of PDF readers with dark mode, too.