Battery
Why won't my Mac sleep? How to find what's keeping it awake
Updated · 5 min read
A Mac that won't go to sleep, or wakes up on its own, is almost always being kept awake by an app, a setting or a connected device. macOS records which, so you can find it directly.
1. Check the Preventing Sleep column
Open Activity Monitor and choose the Energy tab. The Preventing Sleep column shows "Yes" for any app currently keeping the Mac awake. Video players, browsers playing media, download managers and presentation apps are common culprits. See Preventing Sleep.
2. Ask macOS directly
For a complete answer, including system services, open Terminal and run pmset -g assertions. Look for lines like PreventUserIdleSystemSleep with a value of 1, and the process named next to them.
Tip
pmset -g log | grep -i "wake reason" and look at the most recent entries.3. Check the settings that keep a Mac awake
- System Settings › Lock Screen: check when the display turns off on battery and on power.
- System Settings › Battery › Options (on laptops): "Prevent automatic sleeping on power adapter when the display is off" and "Wake for network access".
- System Settings › General › Sharing: sharing services such as File Sharing or Media Sharing can keep the Mac available on the network.
4. Disconnect devices and close media
- Close browser tabs and apps playing audio or video, even if muted or paused in a background tab.
- Unplug external drives, docks and printers to see whether one is waking the Mac.
- Wireless mice and keyboards can wake a Mac when bumped; this is normal.
5. Still awake?
Restart and test again with nothing open. If it then sleeps, add your apps back one at a time to find the culprit. If an app you rely on keeps the Mac awake, check its preferences for an option like "prevent sleep while running".
Notice battery drain while you're away
A Mac that doesn't sleep drains its battery. Tempo for Mac keeps a battery history and can notify you when the battery runs low, so overnight drain doesn't surprise you. Read what's draining my Mac's battery for the bigger picture.