> Summary: In people with normal vision (or corrected-to-normal vision), visual performance tends to be better with light mode, whereas some people with cataract and related disorders may perform better with dark mode. On the flip side, long-term reading in light mode may be associated with myopia.
What is seldom discussed is the different types of dark modes, which are quite radically different in their appearance, purposes, pros and cons (unlike light mode, which is much less variable, and where there is marked variation it’s seldom for any particularly good reason). I wrote a bit about the three or four categories I’ve settled on a couple of years ago: https://news.ycombinator.com/item?id=28516862. It depends heavily on what you’re trying to achieve (æsthetics/low-contrast or accessibility), and the ambient lighting conditions and specific screen technology (both statically unknowable).
All up, dark mode is actually pretty risky, because it can actually at least three radically different and incompatible things. If you implement only one, go light.
Even for users who need light-on-dark, they may want individual sites light-on-dark if they have other sites or apps they have to use that don't have a dark mode so the user inverts the colors on the whole display.