Changing display colours at night

QWhen I wake my Mac up in the evening, its colours are different and the Desktop image has changed. What’s going on?

AThese are optional settings which you might have inadvertently changed, or maybe they’ve been altered by third-party software which you’ve recently installed.

The first controls whether the Desktop Picture and appearance mode change according to the time. In System Preferences, open the General pane, and select either the Light or Dark Appearance, rather than Auto, which changes with time of day.

Then open the Displays pane and its Night Shift tab. This can turn on colour shift intended to use warmer colour during hours of darkness, which some people claim helps you sleep better that night.

The final control which can change the appearance of your display is automatic brightness adjustment which you’ll find in the Display tab.

Set the Appearance to Auto and macOS will automatically switch between Light and Dark modes according to the time.

In the Displays pane, Night Shift changes the colour balance in the evening to make it warmer, which may help your sleep.