Dark Mode or Light Mode: Which One Should You Go With?

The trend is catching up. With dark mode features being inculcated in both Android and iOS applications, an Android or iPhone application developer is turning to make their apps dark mode friendly.

Let’s get into more details and understand what they mean.

The Definition

We use the term Contrast Polarity for describing the contrast between the text and the background.

  • A positive contrast polarity or light mode refers to dark-font text on a light background.
  • On the other hand, a negative contrast polarity or dark mode denotes the combination of light, here, white text on dark or rather black background.

In terms of functionality, dark-mode displays on mobile and tablet screens emit less light than light-mode ones. This is in direct correlation with the extended battery life. However, the overall amount of light in the environment influences not only power consumption, but also our perception. 

Here is some basic information about the eye pupil and how it reacts to the amount of light in the environment in order to understand this concept a bit deeper.

Contrast Polarity Effects on Visual Acuity   

Here is a research to back the claim. At the Institut für Experimentelle Psychologie in Düsseldorf, Cosima Piepenbrock and her colleagues conducted a study on two groups of adults who had normal vision. The participants were  young adults aged 18 to 33 years old and older adults aged 60 to 85 years old. None of those selected participants were suffering from any eye diseases.

The tasks given to them were as follows:

They were presented with a visual-acuity task to detect the gap in a Landolt C optotype. Meaning, they were shown a  symbol similar to the letter “C” oriented in various ways and asking them to identify where the gap is, be it at the top or bottom.

Here is an image representing the aforementioned test.

Another set of tasks was a proofreading one that involved reading a short passage and identifying different types of errors in it.

Researchers presented these tasks in different contrast polarities.  For some participants, they were in dark mode and for others they were in light mode. In this research, each participant saw only tasks in one contrast polarity, for e.g., only dark mode or only light mode.

After the tasks were presented, the researchers collected pre- and post-test fatigue-related measures. Participants were asked to rate their  eyestrain, headache, muscle strain, back pain, and subjective well-being at the beginning of the experiment. And similar ratings were taken after the tests for comparative study.

According to the results, light mode won across all dimensions: irrespective of age, the positive contrast polarity was better for both visual-acuity tasks and for proofreading tasks. 

But, one noticeable factor was that between the light mode and dark mode in the visual-acuity task was smaller for older adults than for younger adults. It stated that although light mode was better for older adults, too, they did not benefit from it as much as younger adults.

In the aspect of fatigue metrics, researchers concluded that there was no significant difference of contrast polarity on any of them. They concluded that there was no solid proof on whether dark mode made people more tired or vice versa.


Is it wise to jump on the dark-mode bandwagon?  It is obvious that dark mode may present some advantages for some low-vision users, the research conducted points in the favour of an advantage of positive polarity for normal-vision users. In users with normal vision, light mode leads to better performance most of the time.

The findings suggest that with positive contrast polarity, there is more overall light and so the pupil contracts more. This creates fewer spherical aberrations, greater depth of field, and overall better ability to focus on details without tiring the eyes or causing fatigue.

It is strongly recommended that designers should allow users to switch between dark mode and light-mode if they want to.  Using only light mode throughout the lifetime is not advisable because i) there can be long-term effects associated with light mode; (ii) a handful of people with visual impairments will do better with dark mode; and (iii) users sometimes simply like dark mode better. 

Those applications meant for long-form reading should definitely have a dark-mode feature for users. Also, designers should not forget taking optimum advantage of those operating systems who provide a dark-mode API. This will give those users who decide to switch to dark mode the ability to experience the application or website in their chosen contrast polarity, thereby enhancing user experience all-in-all.

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