Mac Won’t Sleep; Lion Has Insomnia?
Last night, before I went to sleep, I closed the lid of my MacBook pro (MBP). This morning when I got up, I noticed that it was still running. Lion didn’t sleep for a whole night at all.
Closing the lid of MBP while the machine is running blocks the airflow and could cause the machine over heated. I tried to switch the external hard drive on and off, turn the internet sharing on and off as well. but none had sovled the problem. It seems Mac OS X Lion won’t sleep.
If I unplug the power cord and close the lid then Mac OS X Lion would go sleep in a few seconds without any problems.
Solutions to Lion’s Insomnia:
- Temporary Solution:
Unplug the power cord and then close the lid. Your Mac should be sleeping after a few seconds. Then connect the power cord back.
- Long-Term Solution:
- Open Terminal
pmset -g assertions
Examine the the output, and find out what service is preventing the Mac from going sleep. Line “PreventUserIdleSystemSleep 1” means something is currently preventing the system from sleeping.
- From there, you can “kill” that suspicious process (in my case, it would be
kill -9 22083
) or remove the service that prevents Lion from sleeping. Usually this has things to do with Internet, printer sharing or the secondary external monitor your laptop connects to.
Image Credit: Ryan Tir