Dark UI themes are new and cool — but are they accessible?

They are new and cool, and it is claimed they will help save the environment but are they accessible? The answer is: “sometimes”.

Dark mode is one of those new, hot design features that is generating a lot of “buzz”. Apple and Slack, for example, have been pushing dark themed pages hard lately. However, it appears that not much thought has been given to dark mode accessibility.

I have broken down the claims I have read of the benefits of dark themes into the following categories of “definitely true”, “YMMV” (Your Mileage May Vary), and “not really true”:

Definitely True

• Flicker problems are reduced by dark backgrounds. Definitely true, but only helpful if a flicker issue exists in the first place.
• Dark modes are less prone to triggering photophobia. Definitely true. More white == more photophobia.
• Defective pixels in devices/monitors that are permanently dark don’t show up as much on a dark background. True, but not helpful if your device doesn’t have these issues.
• Easier to use in a dimly lit room. Definitely true.

YMMV (Your Mileage May Vary)

• The most overhyped benefit of dark themes is that it can save electricity. This makes people think “wow, I can save the world if only I switch to dark mode!” However, this is only true on OLED or AMOLED screens. On LCD screens, there is little if no noticeable savings. If there is a savings in electricity it is probably here: Since dark modes are more suitable for use in dimly-lit rooms, the reduced need for ambient lighting will use less electricity. But if you are in an office, you may have no control over ambient lighting. Also, if you have energy efficient lighting that gets its power from renewable / clean sources, that savings may be minimal or zero.
• Improved Text Readability. Maybe, but not for everyone. One of my glaucoma-related issues is I see “halos” (like rings around streetlights at night) when presented with light print on a dark background, which blurs everything into non-readability. This issue is exacerbated with thinner and…