DecodeME website has its own toggle on the bottom page that allows users to choose whether to view the site on light mode or dark mode.

Unfortunately, this toggle could not be implemented on the questionnaire portal due to compatibility issues with the questionnaire iframe, but common dark mode extensions can still be used.

Depending on the type of browser and extension users choose, there is a risk of users experiencing small incompatibility issues (e.g.contrast issues or the questionnaire displaying in light mode))

The Dark reader extension (Dark Reader) showed to be the most compatible with our web-portal, allowing users to access the questionnaire in dark mode and demonstrating good definition of all features that are available in light mode.  This extension is free when using the following browsers:

– Chrome (and browsers that use Chrome extensions e.g. Brave)

– Edge

– Firefox

Unfortunately, this extension is not free-to-use on Safari.

If you would like to access the web portal and questionnaire in dark mode but continue to have difficulties using your dark mode extension of choice, please contact us via email and we will arrange an alternative process for you to participate (

The largest ever DNA study of ME/CFS

A partnership between

Action for ME logo
Forward ME Logo
UKRI MRC Human Genetics Unit logo
National Institute for health research