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OS X: Saving energy with Sleep

Learn about power saving features your Mac uses, including automatic sleep, safe sleep and Power Nap.

energy saver icon

Sleep

When you’re not using your Mac, you can save energy by putting it to sleep. When your Mac is in sleep, it’s on but consumes less power. It takes your Mac less time to wake from sleep than it does to start up after being turned off.

How do I put my Mac to sleep?

To put your Mac to sleep immediately, do one of the following:

  • Choose Sleep from the Apple menu ()
  • Press the Command (⌘) Option and Media Eject key (⏏) simultaneously.
  • If you’re using a Mac notebook computer, close its built-in display.
  • Tap the power button on your computer.

Automatic sleep

Your computer normally sleeps and wakes as needed. When you leave your computer idle, OS X automatically turns off or powers down features that you aren't using. When the computer needs to perform a task, related components are powered back up.

You can change how some features react when left idle, or prevent your computer from sleeping. To select which features of your computer enter a low power mode when left idle, open the Energy Saver pane of System preferences.

  1. Choose System Preferences from the Apple () menu.
  2. Click the Energy Saver icon in the System Preferences window.

energy saver window

Display sleep

You can tell OS X how long to wait before putting your display to sleep. This is useful if your computer is performing a task (such as playing music) but you don't need to see anything the computer is doing. Putting your displays to sleep halts the video signal to internal and external displays connected to your Mac. For Apple displays and built-in displays, this also means that the backlight on the LCD is turned off to save energy.

The display screen goes dark or turns off, but apps that are still busy on your computer remain active. If your display has a power indicator, it may change to indicate that the display is in a low-power mode. To wake your display, move the mouse, touch the trackpad, or press a key on the keyboard.

Put hard disks to sleep when possible

This Energy Saver setting powers down the hard drive motor when you aren't reading or writing files from the drive. This setting only works with computers that use mechanical hard drive mechanisms to store data. Consider deselecting this option if you are using an application that works better with continued read and write access to the hard disk, such as a pro audio or video editing app.

Note: Solid-state drives (SSD) do not use a motorized mechanism to read or write data. For Mac computers that only include a built-in solid-state drive, this setting does not affect the built-in drive. It only applies to externally connected, mechanical drives.

Wake for Network Access

Select this option if you want your computer to automatically wake up when someone accesses its shared resources, such as shared printers or iTunes playlists. This setting applies to the wired connections from other computers such as Ethernet. It also applies to WiFi connections if you are using a properly configured AirPort base station.

Note: Some tasks may prevent the computer from sleeping when idle. See the Troubleshooting section of this article for more information.

Enable Power Nap

Computers using OS X Mavericks include support for Power Nap. This is a special sleep mode that allows your Mac to automatically wake to perform certain tasks, then go back to sleep again when it's finished. This setting in Energy Saver preferences allows you to control whether to let your Mac wake to perform these tasks or, to always sleep. See the Power Nap section of this article for more information.

Additional Options

You may see additional options in Energy Saver preferences depending on whether you are using a desktop or notebook Mac. To learn about these additional settings, select the kind of Mac you are using below.

Mac Pro, Mac mini, iMac

When using a desktop Mac, you can control when your computer, display and hard disks are put to sleep to save energy.

  1. Choose System Preferences from the Apple () menu.
  2. Click the Energy Saver icon in the System Preferences window.

Energy Saver preferences

Computer Sleep

On some Mac desktop computers, you can set how long to wait until the computer enters its lowest idle power mode. This setting is different from display sleep in that other parts of the computer also sleep. If you set the computer to never sleep using this slider, the display and other elements of the computer remain in a fully powered state.

Allow power button to put the computer to sleep

On Mac desktop computers, you can set OS X to prevent users from putting the Mac to sleep when tapping its power button. This can be useful if you are using your computer as a kiosk, or in a classroom environment.

Start up automatically after a power failure

On Mac desktop computers, you can set OS X to automatically restart if its AC power connection becomes unavailable. For example, if there is a power outage, or someone inadvertently disconnects the AC power cord, your computer starts up again on its own once power is reconnected. This is useful if you normally have your computer set to perform tasks when its left unattended. In OS X Lion and later, you can also set OS X to automatically re-open documents you were working on when you log in.

Note: This setting is not available on Mac notebook computers because notebooks include a built-in battery that keeps the computer powered when you disconnect AC power.

MacBook Pro, MacBook Air

On Mac notebooks, you can set some options independently for whether the computer is operating on battery or AC power. For example, you might want your computer to never sleep when you are connected to AC Power. You might also want to set these options more conservatively when your computer is on battery power so that you can use it longer while it's unplugged.

  1. Choose System Preferences from the Apple () menu.
  2. Click the Energy Saver icon in the System Preferences window.
  3. Select the Battery or Power Adapter tab depending on which behavior you want to change.

enable_power_nap

Automatic Graphics Switching

This option appears on computers that have more than one built-in graphics chip. When selected, your computer uses its low power graphics chip for tasks like text editing to save energy. OS X automatically switches to another more complex graphics chip for higher-intensity tasks, like playing games or compressing video.

If you deselect the option for "Automatic Graphics Switching", your computer always uses high-performance graphics. This uses more energy, so you may not be able to use your computer from battery power as long as when Automatic Graphics Switching is enabled.

Special sleep modes

Some Mac computers enter special sleep modes when left idle for an extended period of time. This helps to conserve even more energy. Choose a topic below to learn more about these special sleep modes.

Power Nap

OS X Mountain Lion and Mavericks include Power Nap. This feature allows your Mac to occasionally wake from sleep to perform maintenance such as checking for new email, or for software updates. During Power Nap, your Mac leaves its displays and other hardware that isn't needed for these tasks powered down to save energy. After it's finished, your Mac automatically goes back to sleep to save energy. If you don't want your Mac to wake up on its own to perform these tasks, deselect this option.

Standby Mode

For Mac computers that are started from an solid-state drive, OS X includes a deep sleep mode known as Standby Mode. Mac computers manufactured in 2013 or later enter standby after one to three hours of regular sleep. A computer with a fully charged battery can remain in standby for up to thirty days without being plugged in to an AC power source.

To wake your Mac from standby mode, press a key on the keyboard, or press its power button.

Safe sleep

For Mac computers that are started from an mechanical hard drive, OS X includes a deep sleep mode known as safe sleep. Your Mac may enter safe sleep if your battery begins to run low, or your computer is left idle for a long time. Safe sleep copies the contents of memory to your startup drive, and powers down the computer. This helps you when your battery is depleted on Mac notebooks. All you have to do is connect your notebook to AC power again to pick up where you left off, without losing your work.

To wake your Mac from safe sleep, press its power button. If you are using a Mac notebook and your battery is low, connect the AC adapter first. When waking from safe sleep, a progress indicator appears indicating the previously stored contents of memory are being read from the startup disk, and copied back into RAM.

safesleep

Waking your computer

To wake your computer from any of these sleep modes, tap the computer's power button. Some sleep modes can also be exited by clicking your mouse or trackpad, opening the lid on your Mac notebook, or by pressing a key on a connected keyboard.

If you are using sharing features on your computer, other computers using these services may be able to wake your computer on demand.

More Information

If your Mac doesn't go to sleep when you expect it to, see this article for more information.

Important: Information about products not manufactured by Apple is provided for information purposes only and does not constitute Apple’s recommendation or endorsement. Please contact the vendor for additional information.
Last Modified: Sep 2, 2014
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  • Last Modified: Sep 2, 2014
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