M4 iMac shuts down when asleep, difficult to start up

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Level 2

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M4 iMac shuts down when asleep, difficult to start up

My M4 iMac occasionally shuts down when asleep, and then is difficult to start up. I'm running the latest version of macOS each time it happens. I have two USB drives attached (for Time Machine and SuperDuper).

When I attempt to wake up the iMac after a few hours asleep, sometimes I find the iMac has shut down. It then takes several attempts at the Startup button, and around three cycles of attempts (password entry and re-entry) to get the computer to complete the boot process and allow me to sign in before we are back to normal. Then all is fine until the next unpredictable time this will next occur between a few hours and many days ahead. I sometimes hear a slight click sound from the computer (or possibly one of the attached USB drives) when this cycle of booting and rebooting occurs.

I will appreciate any advice for troubleshooting this not too critical but annoying unpredictable performance.

iMac 24″, macOS 26.3

Posted on Mar 23, 2026 8:24 AM

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Answer 1

Top-ranking reply

-g

Level 4

3,617 points

Mar 23, 2026 9:18 AM in response to jimpal

im of the ones who don’t believe sleep issues (especially nasty ones) are normal or tolerable — you should not have to disable sleep function to enjoy your Mac

i would call AppleCare and get a case number to document the problem

to troubleshoot

remove all non-Apple hardware (to rule out those conflicts) — everything that did not come with the Mac

set up a new admin user (to rule out user settings)

if it clears in new user — your old user is the problem

if it doesn’t clear in new user:

after you have a fresh time machine backup

boot into recovery> disk utility> erase the ssd> reinstall macOS> run the updates

note: on the reinstall you don’t need to set up your Apple ID for testing

if the problem continues at that point — a tech will have a tough time pointing the finger at you and they should not continue wasting your time

if it clears — use migration assistant to bring your time machine into the fresh system

add any extra hardware one at a time…

+++++

ps:

I generally don’t spend more than an hour digging into settings — like vpn, damage done by cleaners — looking for magic bullet, but you could get lucky finding the culprit

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Answer 2

den.thed

Level 10

92,746 points

Mar 23, 2026 8:35 AM in response to jimpal

Full Computer Sleep Mode is causing sleep issues for a lot of setups.

As a test:

Turn On "Prevent automatic sleeping when display is off" in the Energy Settings.

Set "Turn display off when inactive" to 10 minutes in the Lock Screen Settings.

Then:

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

Do not manually Sleep from the Apple Drop Down menu

Shut Down the Mac mini when away for a day or more

Send Feedback to Apple about this issue

Feedback - Mac mini - Apple

Feedback - macOS - Apple

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Answer 3

jimpal Author

Level 2

232 points

Mar 23, 2026 12:07 PM in response to jimpal

I suppose it’s possible that this problem might not occur if I shut down my iMac more frequently. The way I use it is to put it to sleep after I use it each day, sometimes for many days at a time, and just wake it up before each use. Possibly a more frequent shutdown followed by startup would clear things out and possibly prevent this from happening. Who knows?

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Answer 4

-g

Level 4

3,617 points

Mar 25, 2026 5:34 PM in response to jimpal

I recall this iMac was still under AppleCare warranty

disabling sleep may stop the symptom — but it will run out the AppleCare

and may stick the OP with bad hardware

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Answer 5

jimpal Author

Level 2

232 points

Mar 23, 2026 8:50 AM in response to den.thed

Thanks for your prompt response, and letting me know I may not be alone on this. I will try the setup you suggested.

My problem has occurred in a M4 iMac, yet you suggested this setup for a Mac Mini. Is the same setup applicable to both a Mac Mini and a iMac?

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Answer 6

den.thed

Level 10

92,746 points

Mar 23, 2026 1:07 PM in response to jimpal

jimpal wrote:

Thanks for your prompt response, and letting me know I may not be alone on this. I will try the setup you suggested.

You're welcome.

My problem has occurred in a M4 iMac, yet you suggested this setup for a Mac Mini. Is the same setup applicable to both a Mac Mini and a iMac?

Sorry my bad.

Substitute iMac for Mac mini and use the iMac Feedback link.

Feedback - iMac - Apple

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Answer 7

Old Toad

Level 10

216,446 points

Mar 25, 2026 11:21 AM in response to jimpal

I wholeheartedly agree with den.thed regarding not sleeping your Mini. However, I'm old school and shut down my M4 Mini each night. This lets the Mini remove temporary System and application cache and swap files. This helps keep the system and apps running at peak performance.

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Answer 8

jimpal Author

Level 2

232 points

Mar 25, 2026 6:22 PM in response to -g

For -g. I appreciate your continuing attention to this. I find disabling Sleep appealing because of its simplicity. I intend to do that as recommended here by den.thed and Old Toad, unless another fix becomes apparent. A little research shows that many people don't use Sleep at all.

However, you are right that I should get everything working right if possible. I intend to do a bit of experimenting by seeing if I can continue to use Sleep without the problems I mention here by restarting or shutting down my iMac more frequently, and seeing if a connected USB drive is contributing to the problem. I do have AppleCare time remaining, and will be mindful of that before it expires. Thanks for your good advice.

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Answer 9

jimpal Author

Level 2

232 points

Mar 23, 2026 10:20 AM in response to -g

For -g. Thanks for your thorough reply. You've given me some good steps to work through if the simpler den.thed response here isn't helpful for my iMac.

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Answer 10

jimpal Author

Level 2

232 points

Mar 25, 2026 1:50 PM in response to Old Toad

Thanks. I'm going to proceed with this den.thed and Old Toad advice, for now, as it is the simplest. I'll be back to try more if my iMac still has some form of this posted problem.

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Answer 11

Old Toad

Level 10

216,446 points

Mar 25, 2026 2:48 PM in response to jimpal

jimpal wrote:

Thanks. I'm going to proceed with this den.thed and Old Toad advice, for now, as it is the simplest. I'll be back to try more if my iMac still has some form of this posted problem.

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Answer 12

den.thed

Level 10

92,746 points

Mar 25, 2026 4:00 PM in response to jimpal

You're welcome.

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