Updated July 11/’22: The trick described here does NOT allow the Mac itself to sleep. There is apparently no way to disable the (screwed-up) way that the Mac tells the the displays to sleep/wake up AND have the Mac itself sleep automatically.
This post describes a way to make your MONITORS sleep and wake up properly, and lists some things that MIGHT help you with display problems on Macs.
As far as the actual “Energy Saver settings on your Mac go, it seems you can either put up with the annoyance of having your monitors screw up every time the Mac wakes up, or you can never let your Mac sleep.
Displays attached to my Mac Mini (2018) are quite slow and annoying when coming out of sleep.
- Mac Mini (2018), 16 Gigs RAM, MacOS 11.6.6 (Big Sur)
- LG 27’” 4K monitor plugged into the Mini’s HDMI port
- Dell 23” 1080p monitor plugged into HDMI port of a hub off of the Mini’s Lightning port
After sleepytines, the 4K monitor would come on for about 2 secs, then go black, then there would be a 7-10 second pause, then both monitors would come on.
This problem also seems to manifest on some Macbooks with some external monitors. Dunno about iMacs.
What I did that actually fixed this:
- System Preferences—> Energy Saver
- Set “Turn display off after…” to “Never”
Why this works (for me):
Everything works the way it’s supposed to. Normal wake time (~2 seconds) and power saving accomplished!
My completely unsupported theory about this:
I suspect that there is something in the way that the Mini behaves when it is trying to control when the monitors sleep and wake up that causes this problem. Specifically, It’s probably sending a “Wake up” command to the monitor on the HDMI port, and expecting a response. The monitor does not recognise/respond to that command, but detects it as video signal, and wakes up. That’s when the monitor first lights up.
The Mac does not get the response it is expecting from the monitor (even though the monitor has come on) and falls back to what it does when when it doesn’t if a monitor is connected: It probes for/sets up the monitors. That’s when everything goes dark for 7-10 seconds.
Telling the Mac to never turn off the display removes this (unneeded) procedure.
I could probably check if I’m right about this by reading logs or something, but I’m not going to. If you do, I would love to know what you find out.
Other things that people say fix issues like this:
1) If you have a 4K monitor, try NOT plugging it into the HDMI port on the Mac.
Some people have had problems connecting a 4K monitor directly to their Mac via the HDMI port. 1 Connect an adapter/hub to a Lightning/Type C port and then plug the 4K monitor into that.
Note: I tried this, and got the same results as before except the 1080 monitor came on first instead of the 4K. In other words, this had no effect on my problem, BUT it might fix other problems with Macs and 4K monitors. I left my monitors plugged in this way (HDMI port–>1080p monitor, Lightning port –>hub/adapter–>4K monitor).
2) Download new drivers for your monitor
I mean, this is always a swell place to start, but there are no specific drivers or other software for LG monitors on Mac that touch on anything that could affect my issue.
3) Disable FileVault
I am not even kidding. There are people on Apple support boards who swear this it true (or maybe was on earlier version of MacOS). I have to believe that something they did in the course of disabling FileVault (rebooting or something) actually fixed their issue, because I can’t live in a world where people make software that causes these two things to affect each other.
4) Reinstall MacOS
Seriously? I’m using a mainstream monitor on a major operating system in (checks phone) 2022 and we’re going full-wrench to fix a SLEEP ISSUE?
5) Obviously, change2 your operating system to the newest version, because WORKS FINE ON MY MACHINE.
ALWAYS a great idea. I will put this last on this list, and type it ONLY with two upraised middle digits.
1) I KNOW!
2) I don’t always refer to installing newer versions of operating systems as “upgrading” any more, because words mean things. For example, “making a basic function that previously worked and then was broken now work again” is not an “upgrade.”