I did some testing about activities which prevent sleep on Mojave:

It seems that when the display shows a moving image, even if on a background app (such as a youtube video mostly stopped by Finder but still showing movement) prevents sleep, a similar video with a static image but playing audio slept the display (and locked the mac) but didn’t sleep the mac. If the video is playing on another hidden tab, the mac screen or the mac itself (not sure what happened) went to sleep once, not another. No app, nor safari, showed in activity monitor as preventing sleep.

So I wonder

  • Will the mac go to sleep if you let it running a long youtube video?
  • Will the mac go to sleep if it has a cloud app enabled (google drive/dropbox/iCloud drive…)
  • What other activity can prevent a mac from sleeping?

I'm looking for in-depth answers which explain which activities enable or disable sleep on Mojave.

  • 3
    There are lots of things that will prevent a Mac from going to sleep. Issue the command pmset -g assertions to see what is currently keeping it awake
    – Allan
    Commented Apr 15, 2019 at 23:15
  • I've edited your question to focus on the current version of macOS and invite broad answers.
    – nohillside
    Commented Apr 16, 2019 at 5:18
  • Thanks for that. I'll try to find out what those terms shown by this command mean. Commented Apr 16, 2019 at 5:47
  • You never posted the output from the command, so how was anyone supposed to help you?
    – oligofren
    Commented Mar 12, 2020 at 0:31


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