MBP M1 always sleeps when I switch the input on my LG USB-3 monitor.

[richard371]

I currently have my MBP M1 connected via the USB-C input on my LG 27" 4K monitor and I frequently switch to HDMI connection for my work Win machine. Every time I switch back to the Mac its asleep when the display is closed. I have it set to "prevent computer from sleeping when display is off."

 

[jdb8167]

There is an undocumented setting in the command line pmset command that might solve your problem. I haven't tried your exact problem but I use it all the time to keep a M1 MacBook Air in clamshell mode without a power adapter connected from going to sleep.

disable sleep on
sudo pmset -b disablesleep 1

disable sleep off
sudo pmset -b disablesleep 0

Enter your admin password at the prompt(s).

 

[richard371]

Thanks. I may try it but I do want it to sleep when its closed and not plugged into the cable. maybe I can't have it both ways. Workaround is to keep it open a bit when swapping back and forth.

 

[jdb8167]

Thanks. I may try it but I do want it to sleep when its closed and not plugged into the cable. maybe I can't have it both ways. Workaround is to keep it open a bit when swapping back and forth.

I either turn off the setting or use the sleep menu item in the apple menu. I think if you don't have a bluetooth or wired keyboard it will still go to sleep when you close the lid but I'm not positive.