What is preventing your Mac from sleeping, and how to find it with pmset
pmset -g assertions names every process holding a Mac awake. On ours it was a caffeinate call, and powerd while the display was on. How to read the list.
How do I see what is keeping my Mac awake?
pmset -g assertions| Line on our Mac | What it means |
|---|---|
pid 93653(caffeinate): PreventUserIdleSystemSleep ... caffeinate asserting for 300 secs | A tool ran caffeinate to stop idle sleep for 5 minutes at a time |
pid 343(powerd): PreventUserIdleSystemSleep named: Powerd - Prevent sleep while display is on | Normal: the system does not sleep while the screen is on |
pid 400(WindowServer): UserIsActive | Normal: you moved the mouse recently |
pmset -g also summarises it: our sleep line read sleep 1 (sleep prevented by caffeinate, powerd).
Common culprits
- Video and music players, which stop display sleep while playing.
- Downloads, backups and sync tools, which stop idle sleep while working.
- Developer and command line tools using caffeinate.
- Browser tabs playing audio or video, shown under the browser's helper.
- Shared screens and remote sessions.
Quit or pause the app named in the list. To keep a Mac awake on purpose, see caffeinate.
See it live
Free Mac's System tab shows what the Mac is drawing from the adapter and the battery, and ranks what is draining it by energy impact, every second. See also overnight drain.
Related: Read Mac battery data with ioreg and Low Power Mode: what it changes.
Common questions
How do I find what is preventing my Mac from sleeping?
Run pmset -g assertions in Terminal. Each line names a process and what it is preventing.
What does PreventUserIdleSystemSleep mean?
A process has asked macOS not to sleep while idle, usually during a download, backup or caffeinate.
Why does my Mac say sleep prevented by powerd?
powerd keeps the Mac awake while the display is on. That is normal.