Putting your Mac to sleep is perhaps one of the easiest tasks you can do; however, there are several options for doing this that you might not know about, and in addition, if your Mac is either not going or not staying in sleep mode, then there are several things you can try to remedy the situation.

First, to get your Mac to sleep you have anything from menu options to Terminal commands that can get you there:

1. The Apple MenuGo to the Apple menu and choose “Sleep.”
   

   Select “Sleep” in the Apple menu

2. The Power buttonPress the Power button for a second, and then release it, and the system will go into sleep mode.
3. The Power button (again)Press the power button for three-seconds, and the system’s Power menu will display, which contains an option to sleep your system.
   

   The power menu can be invoked by holding the Power button for three seconds.

4. Close the lidIf your system is a laptop, then closing its lid (provided external keyboards and monitors are disconnected), should put it to sleep.
5. The TerminalIf you have a Terminal window open, then you can run the following command to immediately sleep the system:

   pmset sleepnow

6. Your Keyboard
   If you would like a quick hotkey shortcut to sleep your Mac, then just press one of the following sequences, depending on whether or not you have an Eject key on your keyboard:

   Shift-Control-Eject
   Shift-Control-Power

7. Scheduled sleepThe aforementioned options are for you to specifically put your system to sleep; however, you can also schedule your Mac to sleep at a given time in the Energy Saver system preferences. In here, click the Schedule button and then check the box next to the Sleep option, followed by setting a time to sleep your Mac.
   

   Check this box and set a schedule to sleep the system at the appropriate time.

Troubleshooting sleep

If your Mac is not going to sleep, or is not staying in sleep mode. Then there are several things you can do to fix the situation. First, if your Mac goes into sleep mode but then wakes up at random times, read this article to determine why your system is waking up. Then you can try troubleshooting peripheral devices based on what you find, or reset your system’s SMC as possible remedies to this situation.

If your Mac will not go into sleep mode, especially if it is scheduled to do so in the Energy Saver system preferences, then you can try several steps to fix the situation:

1. Check sleep assertionsOS X supports a feature called power assertions, which programs and services can invoke to keep the system from automatically going to sleep or setting the display to sleep. In essence, these are overrides for the power manager’s settings for invoking sleep modes after a given period following no user input (set in the Energy Saver system preferences). To check for the status of sleep assertions, open the Terminal and run the following command:

   pmset -g assertions

   This will output a listing of the available assertions, followed by the number of each that are currently active. Below this list, you will see the specific processes that are invoking the specified assertions. Therefore, if your system will not go to sleep, then consider checking any programs or processes in this list and quitting or reconfiguring them, if you can, to see if that helps the problem at hand.

   

   There are two sleep assertions shown here, one invoked by iTunes and the other invoked by the user actively using the system.

   For example, in the assertions list above, the “PreventUserIdleSystemSleep” assertion is invoked by iTunes playing music in the background, so either stopping playback or quitting this program will turn off this assertion. The other assertion seen is UserIsActive, which is invoked by the “hidd” (human interface device daemon) process, or the background process for handling keyboard and mouse input—in other words, because I am typing on my system at the moment.

2. Restart your MacSometimes odd assertions or other similar configuration you cannot manually manage can be invoked, which will prevent the system from going to sleep. If you cannot pinpoint the issue, then try restarting your system to hopefully clear the problem. You can restart into Safe mode to have the system run some rudimentary maintenance routines, and then restart normally to see if the problem clears itself with this basic troubleshooting step.
3. Reset your System Management Controller (SMC)The System Management Controller is your Mac’s central controller for power-related features, and governs how it goes to sleep, and when it goes to sleep. If this controller is not properly configured, or its configuration is damaged, then it may not sleep your Mac at the time or under the conditions you set. Therefore, try resetting your Mac’s SMC to fix problems with it.