So I’ve been on this hunt for what is preventing my mac from sleeping. This somewhat important because I don’t want to burn in my monitor, as my monitor is susceptible to that sort of issue. Last night I caught at least one culprit.

Slack.

Of course it is Slack. 🤦🏼

I did some more googling as to why this would be the case, and it lead to this article about how the energy tab on the mac activity monitor can be used to help diagnose the culprit in the future.

Source

Looking through the activity monitor I see other apps that are ‘preventing sleep’ but not causing any issues. And after some further googling about slack specifically, the reports seem to be inconsistent. So I don’t know that this THE solution, but I do know that this will be helpful information going forward.

Before I end this, I did want to mention the process of elimination for when you need to search manually through all running programs. You could try removing one application at a time, or only leaving one running at a time, but this is a slow ‘linear’ search method. What you want to do is quit half of your apps. Write down which ones are which. Try again. If it is resolved or not, you now have half the list of items to continue the process. Rinse, Repeat, until you find the offending program. Keep in mind, there could be more than one issue. This is a ‘binary’ search method, it is generally faster. This is a general troubleshooting algorithm, not just for this problem specifically.