Why does my iMac keep waking up from sleep?

Question

Level 1

20 points

Why does my iMac keep waking up from sleep?

For some reason my Mac keeps waking itself up during sleep. On both my wife's account and mine (same Mac). Sometimes it'll stay sleeping for a while, and other times it'll wake up, go to sleep, wake up... The only apps that are consistently running are Safari, Photos, mail Mail or Music, sometimes our chat program (though we aren't getting messages when it's waking)...

Any way to know what's waking it up? And even better, how can I stop it?

iMac 24″, macOS 15.6

Posted on Sep 9, 2025 3:50 AM

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Answer 1

den.thed

Level 10

89,074 points

Sep 9, 2025 9:09 AM in response to kevtron82

As a test, try the following settings.

Turn On "Prevent automatic sleeping when display is off"

Set "Turn display off when inactive" to 5 or 10 minutes

Leave the iMac On and only allow the display(s) to turn Off

Do not manually Sleep from the Apple Drop Down menu

Shut Down the iMac when away for a day or more

Other things that can turn the display back on or wake a sleeping Mac are:

the slightest movement from a USB keyboard or mouse

polling or activity from an external backup drive

slight serges or drops in the main power

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Answer 2

tbirdvet

Level 6

16,735 points

Sep 9, 2025 4:24 AM in response to kevtron82

Usually it wakes from network access requirements. That being said most now recommend not using sleep as it can cause several different issues so just have display turn off after a set time. Do not use sleep.

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Answer 3

kevtron82 Author

Level 1

20 points

Sep 9, 2025 4:46 AM in response to tbirdvet

I don't actually have 'sleep' turned on I think. In the Lock Screen options it's just set to turn off the monitor after 10 minutes. In the Energy settings should I click the 'Prevent automatically sleeping when the display is off' then?

In those same energy settings I actually already have 'Wake for network access' checked off. So that would mean something else is waking it up yeah?

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Answer 4

tbirdvet

Level 6

16,735 points

Sep 9, 2025 7:00 AM in response to kevtron82

Yes you need to prevent sleeping when display is off

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