OS X Mountain Lion: If your Mac won’t go to or stay in sleep

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If your Mac won’t go to or stay in sleep

If your Mac doesn’t go to sleep when you expect it to, or if it wakes up unexpectedly, you may need to change your sleep preferences or something may be waking your computer.

  • Make sure your computer’s sleep settings are set the way you want. In Energy Saver preferences, use the slider that controls the computer’s sleep.
  • Other users may be waking your computer remotely to use its shared resources. If you don’t want this to happen, open Energy Saver preferences and deselect “Wake for network access.”
  • Bluetooth devices can wake your computer. If you don’t want a Bluetooth keyboard or mouse to be able to wake the computer, open Bluetooth preferences, click Advanced, and then deselect “Allow Bluetooth devices to wake this computer.”
  • Key presses and mouse or trackpad clicks can wake your computer. If your computer wakes when you’re not present, something may be pressing the mouse button or keyboard.
  • Apps that access a disk can keep your computer from going to sleep. For example, iTunes accesses your disk to read the songs it plays, and DVD Player accesses the optical disc drive to play movies.
  • People using shared services on your computer can prevent it from sleeping. For example, they may be using a printer connected to your computer or accessing shared files stored on it. In Sharing preferences, turn off any services you don’t need to use by deselecting the On checkbox next to the service.
  • If Spotlight is indexing your hard disk, your computer won’t go to sleep. Click the Spotlight icon on the right side of the menu bar and check whether it says it’s indexing. Indexing your files can take several hours, depending on the number of files on your computer.
  • Malfunctioning USB, FireWire, and Thunderbolt devices may keep your computer from going to sleep. Disconnect those devices and see if your computer goes to sleep. If it does, reconnect each device, one at a time, until you find the one that’s malfunctioning. Contact that device’s manufacturer for more information.
  • Some PCI extension cards intentionally prevent a computer from going to sleep. Refer to the documentation that came with your card.
Published Date: Sep 4, 2015