Instructions for manually enabling power management
Mac OS X
Click on the apple symbol (Apple Menu) in the upper left of your screen.
Go to "System Preferences," Click "Show All" and select "Energy Saver" from the "Hardware" row.
Click on the "Show Details" button. Select "Power Adapter" under "Settings For:" If you are unable to complete this step an administrator has prevented you from changing these settings. Please stop here.
Set "Put the computer to sleep when it is inactive" to 30 minutes (or less) using the slider.
Check the box for "Use separate time to put the display to sleep" and set the time to 15 minutes (or less) using the slider.
Check the box for "Put the hard disk to sleep when possible."