Why is my Mac “falling asleep” when it's told not to?

Question

MY power settings are for "NEVER" when it comes to sleeping with AC power. AC power is always on. So why always when I come to the Mac after hours of being away, it awakes from sleep, loads up all the programs, signs back into skype etc. Where is the hidden setting that causes it to do that?

It only does it at home, another MBP I have at work doesn't exhibit this strange behavior.

Answer 1

Check Your Log Files

You can use the Console.app application to review your Mac's system.log. This file will include entries stating when your Mac went to sleep. You may even be lucky enough to see an entry hinting at why sleep was initiated.

Confirm Your Active Energy Saving Settings

You can check the current Energy Saving settings using the pmset command line tool.

The following command will display all the energy saving settings. You will need to enter this command in the Terminal.app in Applications > Utilities:

pmset -g

In the results, look for the sleep, displaysleep, and disksleep values. These are all measured in minutes.

The pmset manual explains what the various settings mean and the options you can change using this tool.

Answer 2

Is your computer actually sleeping, or is it a display sleep that looks like a real sleep?

What about the other options in Energy Saver, like "Put hard disk to sleep when possible" (unchecking this may help with being logged out of some chat programs) and "Wake for network access" (checking this helps with other chat programs)?

Also check the schedule button to make sure no sleep schedule got accidentally set.

In my experience, all of the sleep options are controlled from the Energy Saver panel, so I'd check your system preferences first. If that doesn't do it, check the settings in any third-party system extensions you have that might deal with power or computer performance.