First, let’s open “Activity Monitor.” You can locate the app in your Applications > Utilities folder, or you can use “Spotlight.” Click the “magnifying glass” icon in your menu bar, or press Command+Space. When a search bar pops up, type “activity monitor” and hit “Return.”

When Activity Monitor opens, click the “Energy” tab.

In the “Energy” tab, you will see a list of active processes (apps and background system functions) with information on their energy impact. Look for a column header labeled “Preventing Sleep,” and click it.

If you see a “Yes” listed in the “Preventing Sleep” column, then your Mac will not automatically engage sleep mode while that process is still active. If it’s a process you recognize, you can wait for an active task to finish, or try to “Quit” the app. If it’s a process that is not behaving as you expect or is refusing to close, you can force it to quit.

To force a process to close in Activity Monitor (on any tab), select the process in the list and click the “Stop” button, which looks like a small octagon with an “X” inside.

When Activity Monitor asks you to confirm, click “Force Quit.” After that, if that process was the only thing holding up your Mac’s sleep mode from engaging, then your Mac should go to sleep the next time you expect it to.

If Your Mac Still Won’t Sleep

If you didn’t find an app preventing sleep listed in Activity Monitor, you can dig deeper into the problem using a command line tool called pmset. However, that tool requires much deeper Mac troubleshooting experience to figure out the cause of the sleep problem. Whatever happens, don’t stay up all night trying to figure it out—remember to get some sleep yourself. If you’re having trouble, try a glass of warm milk.