What is corebrightnessd and why is this process running on my Mac?

When looking into the Activity indicator Have you discovered the corebrightnessd process on your Mac and now want to know what it actually does? No problem, because below I have put together the most important information about this macOS background process. The good news right from the start: it is save malicious software! And the second good news: If corebrightnessd uses 100% CPU on your Apple Mac or causes other problems, there are a few solutions you can try.

What is corebrightnessd and what is the task of this macOS process on the Apple Mac? Here you will find information about this as well as tips for troubleshooting if the CPU load is too high.
What is corebrightnessd and what is the task of this macOS process on the Apple Mac? Here you will find information about this as well as tips for troubleshooting if the CPU load is too high.

The corebrightnessd process on the Mac: Managing Night Shift

The name of this macOS background process is a bit misleading. Because you write it as Core Brightness Daemon, then at first glance it seems as if the process takes care of the brightness of the display. But that's only half true, because it manages the so-called "Night Shift" function. The corebrightnessd process ensures that the display acquires or loses a reddish color - depending on the schedule set.

The Daemon is started automatically by the operating system. He also acts largely independently. The only thing you have to set up manually is Night Shift and, if necessary, the associated schedule and desired color temperature. This can be done via the Mac's system settings: Apple logo -> System settings ... -> Displays. This method works in both the old design (up to macOS 12 Monterey) and in the new design (from macOS 13 Ventura). Once there, click on the “Night Shift…” button.

Problem on Mac: corebrightnessd uses too much CPU

It is rare for the corebrightnessd daemon to cause problems. There were corresponding discussions on the topic on the Apple Community website in 2017 about macOS 10.13 High Sierra, but apparently due to a bug that caused the cases of corebrightnessd with over 100% CPU consumption to increase slightly. However, if this rare case occurs to you and the process causes a high processor load, then you can try these solutions:

  • Stop the process from Activity Monitor and see if it works normally again after it restarts automatically
  • Restart the Mac (switch it off completely and then switch it on again)
  • Disable Night Shift in the settings shown above
  • Adjust the Night Shift settings (use the automatic one instead of an individual schedule or vice versa)
  • A combination of several steps: set the color temperature to the average, deactivate Night Shift, restart the Mac, activate Night Shift again

In addition to the options that the Mac and its operating system offer for troubleshooting with Night Shift or the corebrightnessd process, you should also consider third-party apps. Do you use e.g. B. a system extension or a software tool that is intended to make using your Mac easier through automation or one-click solutions, the problem could also lie there.

If you control Night Shift via a third-party solution instead of directly via the macOS settings, the CPU problems could possibly be solved by quitting the corresponding app (and possibly restarting the process or system). If you don't want to do without Night Shift or the app, then report the problem that occurs in combination to the developers so that they can solve it with an update.

Summary: The process is a normal part of the operating system

The corebrightnessd background process is a macOS daemon, i.e. a completely normal part of the system that acts automatically to make the Mac easier to use. If you have activated Night Shift, this process ensures that the screen is adjusted in the selected manner at the desired times. If movements or animations suffer from the “Night Shift” function, then the color temperature is reduced a few levels. If corebrightnessd has problems, try the list above or, if necessary, deactivate Night Shift until an update solves the underlying problem. 

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In the Sir Apfelot Blog you will find advice, instructions and reviews on Apple products such as the iPhone, iPad, Apple Watch, AirPods, iMac, Mac Pro, Mac Mini and Mac Studio.