Sleep (OS X)

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Sleep on Macintoshes running on OS X consist of the traditional sleep, Safe Sleep, and Power Nap. In System Preferences, Safe Sleep[1] is referred to as sleep. Since Safe Sleep also allowed state to be restored in an event of a power outage, unlike other operating systems, hibernate was never offered as an option.

In 2005, some versions of Macs running Mac OS X v10.4 began to support Safe Sleep. The feature saves the contents of volatile memory to the system hard disk each time the Mac enters Sleep mode. The Mac can instantaneously wake from sleep mode if power to the RAM has not been lost. However, if the power supply was interrupted, such as when removing batteries without an AC power connection, the Mac would wake from Safe Sleep instead, restoring memory contents from the hard drive.[2]

Safe Sleep capability is found in Mac models starting with the October 2005 revision of the PowerBook G4 (Double-Layer SD[vague]). Mac OS X v10.4 or higher is also required. A hack enabled the feature as well on older Macs running Mac OS X v10.4.[3]

In 2012, Apple introduced Power Nap with OS X Mountain Lion (10.8) and select Mac models.[citation needed] Power Nap allows the Mac to perform tasks silently,[vague] such as iCloud syncing and Spotlight indexing. Only low energy tasks are performed when on battery power, while higher energy tasks are performed with AC power.[citation needed]

Mac models supporting Power Nap[4][5]
Since Model
OS X 10.8.2 MacBook Pro (Retina, Early 2013)
OS X 10.8.0 MacBook Air (Mid 2012)
OS X 10.8.0 MacBook Air (Mid 2011)
OS X 10.8.0 MacBook Pro (Retina, Mid 2012)
OS X 10.8.2 MacBook Air (Late 2010)
OS X 10.9.0 Mac mini (Late 2012)
OS X 10.9.0 iMac (Late 2012)
OS X 10.9.0 Mac Pro (Late 2013)