You can automatically shift between light and dark themes using the "Scheduled Themes" feature on Xbox One. Here's how.
In late 2017, Microsoft debuted a "light theme" for its Xbox One console, giving users the option to shift the OS color scheme away from its formerly darker tone. Reworking the entire Xbox One OS, the light theme favors whites and lighter colors, which makes for improved visibility in brighter environments. Alternatively, the dark theme still utilizes blacks and dark grays, which can be easier on the eyes once the sun sets.
Full story from the WindowsCentral blog...