Make Your Mac Sleep More Efficiently with SafeSleep

Jackson Chung 08-03-2009

safe sleep macOne of the many things Mac users are proud of is the fact that we never have to turn our Macs off. Macs are built to run for days, weeks, months and even years (in some instances) on end without ever restarting. And it hardly ever feels bogged down.


If my Mac isn’t performing any tasks and if I won’t be using it, I’ll set it to sleep. How to put mac to sleep? That’s equivalent to Standby mode on Windows computers. Since the PowerBook G4, all portable Macs including the MacBook, MacBook Air and MacBook Pro have a separate sleep mode known as Safe Sleep.

Set as the default sleep mode for portable Macs in 2005, Safe Sleep is a combination of sleep and hibernation modes. At the initiation of sleep, the contents on your main memory will be stored as a sleep image on the RAM and written on the hard disk. The memory is kept powered but if the battery is depleted, the Mac will shut down. After an adapter is plugged in and the Mac is switch on, it will load the sleep image which was saved to the hard disk and restore your workspace.

While this approach is, as they call it — safe; the whole process of initiating sleep is slower because the sleep image has to be written to the hard disk. There are 2 other sleep modes you should know about.

Sleep Only

Also known as mode 0, this is the old-school sleep mode. Only the RAM is powered during sleep, nothing is written to the hard disk so the process of sleep initiation is much quicker and so is waking it up. The downside is the lack of a backup if the battery runs out of juice while sleeping. The advantage: sleep is almost instantaneous.

Hibernation Only

Also know as mode 1 (or 5, for secure virtual memory), the contents of the memory are written to the hard disk, the entire Mac powers down. In this mode, sleep initiation takes the same amount of time Safe Sleep. Waking up also takes slightly longer than the normal sleep mode since it has to read the sleep image from the hard disk. This mode is equivalent to Hibernate on Windows computers.


I use this mode when I have to leave my Mac idle for longer durations but don’t really want to shut it down and also to save power. The duration to start up from this mode is somewhere in between a normal boot and waking from sleep — around 10 seconds.

On waking, a progress bar will be displayed as the sleep image is read from the hard disk to restore your workspace.

Image from Apple KB

safe sleep macbook


And now, SmartSleep

Brought to you by the same guy who developed JollysFastVNC, SmartSleep combines the best of both worlds. It even defeats Safe Sleep at its own game.

SmartSleep is a preference pane which will allow you to set the sleep mode you desire (described above).

how to put mac to sleep

In addition to that, it introduces a new sleep mode: um, SmartSleep. Using SmartSleep, the ‘Sleep Only’ mode is used to put your Mac to sleep. In the case that the battery level drops below 20%, it will switch to Safe Sleep and write the sleep image to the hard disk. SmartSleep makes your Mac sleep quicker without jeopardizing the safety of your data.


What you should know

While Safe Sleep is slow, it is very useful. For instance, during sleep, the battery can be safely removed/changed without worrying about losing data since it has already been written to the hard disk. SmartSleep does not replace this feature because hibernation only kicks in at 20% battery level.

SmartSleep requires OS X 10.5 to run (although reported to work with 10.4 also) and needs to be installed for all users.

How long has your Mac gone without restarting? Which sleep mode do you use? Let us know in the comments.

Related topics: Health, Sleep Mode.

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  1. Michele
    March 14, 2009 at 7:45 am

    Very very very great! This is what I was looking for!
    I'm going to set my MacBook on "Hibernate only", to save battery and also to save power.

  2. Paul Dong
    March 8, 2009 at 11:35 pm

    what i truly want to know is how to disable that damn light when my Macbook is asleep.

    I know it's kinda cute, but it just kept on blinking at me at night!

    • Chrisznix
      March 9, 2009 at 11:11 am

      Well, then set it to "hibernate only", and everytime it will power down - and the light is off.

      • Paul Dong
        March 9, 2009 at 7:57 pm

        wow, it's that easy! thanks buddy

      • Paul Dong
        March 10, 2009 at 8:04 pm

        Well, i tried but couldn't find the configuration anywhere. Do I have to install a software to do that? I have Deeper and Onyx installed.

        • Jackson
          March 11, 2009 at 4:24 am

          You need to install the featured software -- SafeSleep

    • Jackson
      March 10, 2009 at 6:49 am

      OR you could just put a bit of black cloth in front of the light :)