I'd like to have my new Mac Mini turn off the display and sleep after 30 min. of inactivity. Under System Settings/Energy, the option to "Prevent automatic sleeping when the display is off" is off. And Lock Screen: "Turn display off when inactive is set to 30 min. (But the display doesn't turn off even after 2 hours or more). I can manually put the mini to sleep, restart, and shut down.
Mac mini, MacOS 27.0.1, Samsung monitor
My new Mac mini (macOS 27.0.1) does not turn off its Samsung monitor automatically, even after two hours of inactivity. In System Settings >> Lock Screen, “Turn display off when inactive” is set to 30 minutes. Under System Settings >> Energy, “Prevent automatic sleeping when the display is off” is Off. I can put the Mac to sleep manually, restart it, and shut it down without any problems.
I'd start by confirming that the 30-minute setting is still in place. Close applications that might be playing media or running presentations, then leave the Mac untouched for 35–40 minutes. Check that the keyboard or mouse isn't generating unexpected activity. Apple's guide to sleep and wake settings explains the relevant options.
If the display still stays on, check whether an application is preventing it from sleeping. Open Applications >> Utilities >> Activity Monitor, select CPU, and look for unusual activity or a “Preventing Sleep” column, if available.
You can also open Terminal and run pmset -g assertions.
Look for active PreventUserIdleDisplaySleep or PreventUserIdleSystemSleep assertions and the processes responsible. These can provide useful clues, although they may not explain every display-sleep problem.
Next, temporarily disconnect non-essential USB and Thunderbolt devices, including external storage, and test again.
If Spotlight is indexing, allow it to finish before retesting. You can also temporarily turn off sharing services you don't use under System Settings >> General >> Sharing. If disconnecting a device helps, reconnect devices one at a time to identify the cause. Apple's guide, If your Mac sleeps or wakes unexpectedly, provides further troubleshooting advice.
If you're using a dock, hub, or adapter, connect the Samsung monitor directly to the Mac mini, if possible, and check the monitor's own power-saving settings. If the problem continues, check for compatible macOS updates and consider testing in safe mode to see whether software that loads at startup is involved. Apple's instructions are available under Start up your Mac in safe mode.
Your existing Energy setting is correct, so there's no need to change it for now. Laptop battery settings do not apply to the Mac mini.
One question would help narrow this down: after 30 minutes of inactivity, does the Samsung monitor continue showing your desktop, or does it go black and then turn back on by itself?
My new Mac mini (macOS 27.0.1) does not turn off its Samsung monitor automatically, even after two hours of inactivity. In System Settings >> Lock Screen, “Turn display off when inactive” is set to 30 minutes. Under System Settings >> Energy, “Prevent automatic sleeping when the display is off” is Off. I can put the Mac to sleep manually, restart it, and shut it down without any problems.
I'd start by confirming that the 30-minute setting is still in place. Close applications that might be playing media or running presentations, then leave the Mac untouched for 35–40 minutes. Check that the keyboard or mouse isn't generating unexpected activity. Apple's guide to sleep and wake settings explains the relevant options.
If the display still stays on, check whether an application is preventing it from sleeping. Open Applications >> Utilities >> Activity Monitor, select CPU, and look for unusual activity or a “Preventing Sleep” column, if available.
You can also open Terminal and run pmset -g assertions.
Look for active PreventUserIdleDisplaySleep or PreventUserIdleSystemSleep assertions and the processes responsible. These can provide useful clues, although they may not explain every display-sleep problem.
Next, temporarily disconnect non-essential USB and Thunderbolt devices, including external storage, and test again.
If Spotlight is indexing, allow it to finish before retesting. You can also temporarily turn off sharing services you don't use under System Settings >> General >> Sharing. If disconnecting a device helps, reconnect devices one at a time to identify the cause. Apple's guide, If your Mac sleeps or wakes unexpectedly, provides further troubleshooting advice.
If you're using a dock, hub, or adapter, connect the Samsung monitor directly to the Mac mini, if possible, and check the monitor's own power-saving settings. If the problem continues, check for compatible macOS updates and consider testing in safe mode to see whether software that loads at startup is involved. Apple's instructions are available under Start up your Mac in safe mode.
Your existing Energy setting is correct, so there's no need to change it for now. Laptop battery settings do not apply to the Mac mini.
One question would help narrow this down: after 30 minutes of inactivity, does the Samsung monitor continue showing your desktop, or does it go black and then turn back on by itself?
I think I have fixed the problem. After turning OFF "Prevent automatic sleeping when the display is off”, the mini went to sleep and the display went Black! Of course I had the option to turn the monitor off manually but that's not a problem. Thanks for your help.
OK
Copy the below text exactly as it is presented
pmset -g assertions
Open the Terminal Application
⌘ + V into Terminal
Press the return key
What do you get
Easy
Open the Terminal Application
% pmset -g assertions
2026-10-12 07:32:45 -0400
Assertion status system-wide:
BackgroundTask 0
ApplePushServiceTask 0
UserIsActive 1
PreventUserIdleDisplaySleep 0
SoftwareUpdateTask 0
PreventSystemSleep 0
PreventSystemSleepSecurityIndicator 0
ExternalMedia 0
PreventUserIdleSystemSleep 1
NetworkClientActive 0
Listed by owning process:
pid 165(bluetoothd): [0x000034fb00018df8] 00:00:02 PreventUserIdleSystemSleep named: "com.apple.BTStack"
pid 165(bluetoothd): [0x0000000c0009805f] 03:45:52 UserIsActive named: "Bluetooth Incoming Connection Request"
pid 171(WindowServer): [0x000000130009808d] 00:00:00 UserIsActive named: "com.apple.iohideventsystem.queue.tickle serviceID:100000ee9 service:AppleHIDKeyboardEventDriverV2 product:P.?s Magic Keyboard eventType:3"
pid 517(sharingd): [0x000033a000018dac] 00:05:49 PreventUserIdleSystemSleep named: "Handoff"
pid 116(powerd): [0x000000080001800e] 03:45:57 PreventUserIdleSystemSleep named: "Powerd - Prevent sleep while display is on"
pid 116(powerd): [0x000000080009800f] 03:45:57 UserIsActive named: "com.apple.powerd.ws.initialize"
Kernel Assertions: 0x100=MAGICWAKE
id=565 level=255 0x100=MAGICWAKE creat= description=en1 owner=IOSkywalkNetworkBSDClient
Last login: Mon Oct 12 08:21:19 on console
The default interactive shell is now zsh.
To update your account to use zsh, please run `chsh -s /bin/zsh`.
For more details, please visit Page Not Found - Official Apple Support
iMac2:~ JeffK$ pmset -g assertions
2026-10-12 08:34:11 -0400
Assertion status system-wide:
BackgroundTask 0
ApplePushServiceTask 0
UserIsActive 1
PreventUserIdleDisplaySleep 0
SoftwareUpdateTask 0
PreventSystemSleep 0
PreventSystemSleepSecurityIndicator 0
ExternalMedia 0
PreventUserIdleSystemSleep 1
NetworkClientActive 0
Listed by owning process:
pid 422(WindowServer): [0x0000001a00098050] 00:00:00 UserIsActive named: "com.apple.iohideventsystem.queue.tickle serviceID:100001455 service:AppleHIDKeyboardEventDriverV2 product:Jeffry?s Magic Keyboard eventType:3"
Timeout will fire in 1800 secs Action=TimeoutActionRelease
pid 415(bluetoothd): [0x000002f000018475] 00:00:45 PreventUserIdleSystemSleep named: "com.apple.BTStack"
pid 415(bluetoothd): [0x0000001d00098151] 00:12:47 UserIsActive named: "Bluetooth Incoming Connection Request"
Timeout will fire in 1033 secs Action=TimeoutActionRelease
pid 642(cloudd): [0x0000031a000c8510] 00:00:03 SystemIsActive named: "NSURLSessionTask 6FD54DC8-7994-49BE-B9BE-6FFE30C8FD01"
Timeout will fire in 10797 secs Action=TimeoutActionTurnOff
pid 663(sharingd): [0x0000030300018507] 00:00:26 PreventUserIdleSystemSleep named: "Handoff"
pid 366(powerd): [0x0000001800018008] 00:12:52 PreventUserIdleSystemSleep named: "Powerd - Prevent sleep while display is on"
pid 366(powerd): [0x0000001800098009] 00:12:52 UserIsActive named: "com.apple.powerd.ws.initialize"
Timeout will fire in 1027 secs Action=TimeoutActionRelease
Kernel Assertions: 0x104=USB,MAGICWAKE
id=562 level=255 0x4=USB creat= description=com.apple.usb.externaldevice.01100000 owner=1080P Pro Stream
id=570 level=255 0x100=MAGICWAKE creat= mod= description=en1 owner=IOSkywalkNetworkBSDClient
What keyboard and mouse are connected to the Mac mini..?
What USB drives and devices are connected to the Mac mini…?
What Samsung display and how is it connected to the Mac mini…?
What third-party Apps are installed and running on the Mac mini…?
Referance articles:
Put your Mac to sleep or wake it - Apple Support
You are welcome
🦉-53
BTW: How do I run pmset -g assertions in the Terminal app? I have never used that.
Easy? LOL. Like I said, I've never used the Terminal before and I've never entered code either. If you have the time, please guide me with "Type: (whatever)and "Then type:...
Mac mini display not turning off after inactivity
