OS X Mavericks: Prevent your Mac from sleeping
Some Mac computers go to sleep automatically after a period of inactivity. If your Mac supports it, you can prevent it from going to sleep if you need to continue performing a task, such as burning a CD or DVD.
- Choose Apple menu > System Preferences, then click Energy Saver.
- Drag the slider that controls the computer’s sleep to Never, or select “Prevent computer from sleeping automatically when the display is off” if the checkbox is available.
When the Mac finishes the task, change the settings in Energy Saver preferences so that your Mac goes to sleep when it’s not in use.