Q: How do I lock the screen or put a computer to sleep using Mac OS X?

Q: How do I lock the screen or put a computer to sleep using Mac OS X? Answer. There are different ways to lock a Mac computer screen - that is, making the screen go to "sleep" and then requiring a password to "wake it up." This is a good habit to have when leaving a computer during a short period of time rather than completely booting down/shutting down the computer or even logging off. When to lock a computer: When stepping away from your computer for longer than a few minutes. To save energy. To save the life of the monitor - some monitors can "burn out" if left on for long periods of time. If the workstation is in an open area and you are not always at your desk. Three different ways to lock a computer: Go to the Apple menu and select Sleep. Hold down the keys OPTION+COMMAND+EJECT simultaneously. One of the corners of your screen can be a Hot Corner. Setting the pointer of your mouse in the Hot Corner will put the screen to sleep. See System Preferences > Desktop & Screen Saver > Screen Saver > Hot Corners. Then activate a corner by selecting Put Display to Sleep from the drop down menu corresponding to that corner..