How Do I Turn Off My Display In OS X Mavericks?
The behavior of the power button has been modified in OS X Mavericks. Previously, if you tapped the power button it would bring up the system power dialogue that shows options for Sleep, Restart, and Shut Down. Now if you tap the power button it will turn off the display. Hold the button for a couple seconds to bring up the power dialogue or hold for about ten seconds to shut down the MacBook completely.