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What's the difference between Sleep, Standby, and Hibernate?

Standby puts your computer into energy-saving mode, where it uses very little power.

Hibernate saves your workspace (all your open windows), then turns the computer off.

The difference is that hibernate saves more energy because the computer goes off completely, but it takes longer for the computer to wake up from hibernation, so it's not as convenient.


Energy Use

1-6 watts
0 watts

Time to sleep/wake up

a few seconds
30 secs. to 3 minutes

Sleep is more complicated, because it means different things on different computers.

  • Mac OS, desktop. Sleep is the same as Standby. There is no built-in way to Hibernate.
  • Mac OS, laptop. Sleep initially means Standby, but if the battery level drops very low then the laptop automatically Hibernates. See below for more on this.
  • Windows Vista. Sleep initially means Standby, but it switches to Hibernate if the battery level drops too low (laptop) or the computer has been sleeping for more than three hours (both desktops & laptops). You can change the 3-hour period to something else in Settings > Power Options.
  • Windows XP. ???


Hibernate on Windows Vista

     As mentioned above, Hibernate happens automatically in Windows Vista for both laptops and desktops after the computer has been sleeping for a while. Laptop users can skip to the chase and just choose Hibernate manually. That option isn't available to desktop users by default, but this article shows how to enable Hibernate for desktop computers. It's also helpful if the Hibernate option has disappeared from your laptop for some reason.


Hibernate on Mac OS ("Safe Sleep")

     Apple calls Hibernation "Safe Sleep". That's what I'll call it too for the rest of this article.

     Apple doesn't see fit to let the user choose Safe Sleep on their computers.  Safe Sleep happens on laptops only if it's sleeping and the battery level drops too low, and even then only on PowerBooks made after October 2005.  You can override that behavior and get your Mac (laptop or desktop) to Safe Sleep immediately on demand with software like Deep Sleep, SmartSleep, or  SuspendNow (or see the hacks at Mac Simple Life or MacWorld).

     (Trivia: Apple used to let users choose Safe Sleep. On the old clamshell iBooks, circa 2000-01, running Mac OS 9, there was an option called "Preserve memory contents on sleep".)

Which should you use:  Standby, Hibernate, or Shut Down?

     You probably want Standby, because it's the most convenient.  With Standby it takes only a few seconds for your computer to wake up.  With Hibernate or Shut Down, you have to wait 30 seconds to 3 minutes for it to start up again.

     Hibernate or Shut Down will save more energy, but not much.  Six watts x 23 hours a day x 30 days a month is 4.1 kWh, which at 15/kWh would cost you 62/mo.  If that kind of savings is important to you, then sure, hibernate or shut down your computer.  Otherwise, just set your computer to standby so that it wakes up quickly the next time you want to use it, and don't worry about the very small difference in energy use.


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Is this article inaccurate or outdated?

If you spot any errors or missing info, please let me know.


Last update: November 2010

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