Visual fatigue This is long established. For instance, there’s a research paper supporting this back in 1988 (see link to ‘Reading from Paper versus Reading from Screen’).
This paper also cites earlier studies in 1986 from Cushman & Gould drawing the same conclusions. In 6 45-minute work periods, they compared ‘negative polarity’ (Dark UI – in this case light green text on a dark green background) vs positive polarity’ (Light UI).
There was ‘faster reading from dark characters on a light background’. Qualitative information gathered confirmed increased eye strain with negative polarity.
They were also able to rule out other factors such as screen orientation, screen flicker etc.
It’s all about light conditions Dark mode doesn’t directly reduce eye strain. Neither does light mode.
“In a dim setting, a bright screen has your eyes working harder. On the contrary, a dark screen in a brightly lit room will have the same effect.” Retinal specialists, Empire Retina (link below ‘How Environment impacts Eye Strain in Dark Mode’)
So, dark screens in a low-lit room. Light screens in a well-lit room. In addition, the most important factor to reduce eye strain, is to maximise colour contrast. Light UI has higher colour contrast.
The only time Dark UI would always be preferable, would be for those who are sensitive to light.
Contrast Sensitivity and Age-Related Macular Degeneration
Contrast Sensitivity relates to the difference between two colours, shades, or tones. Studies show that there is a linear decline in contrast sensitiviy, when comparing those aged 20-30 years and those 50-80+. See below link to ‘Effect of age on contrast sensitivity’.
Dark UI has less contrast than Light UI. In bright environments, this adds additional eye strain.
Is your target audience more likely to be in the older age bracket, such as business owners? If so, having a site designed using Dark UI may encourage visitors to leave your site before getting in touch.
There Every Moment of the Day The goal of every social media platform is to keep you on there from the moment you awake to the moment you want to get to sleep.
So, a Dark UI option is essential for getting you back for another session after receiving a new notification.
Especially for Business to Business sites, a dark mode is less essential, as mostly they tend to be viewed during the working day.
Arielle Pardes, Wired writes, “Twitter, for example, found that users spent more time in its app when dark mode was turned on. You’re less likely to notice that your eyeballs have dried out from staring into your screen.”
Its crucial to remember though, dark mode is best for scanning, not deep reading. Hence its success with short snippets on social media.
See more on the link to Halo Lab: ‘Benefits of Dark UI’.
Reading from Paper versus Reading from Screen Research study (Oct 1988) by A. Dillon, C. McKnight, J. Richardson Read more
How Environment impacts Eye Strain in Dark Mode Dr. Aizman – Empire Reina Consultants Read More
Effect of Age on Contrast Sensitivity British Medical Journal Read More