Tweak the Mac sleep settings to sleep faster or longer

There is more to sleep mode on the Apple Mac than you might think and there are hidden settings, different modes and keyboard shortcuts. Here is everything you need to know.

Go to the Apple menu on your Mac and there is an option to put the Mac to sleep. It looks like it shuts down, but it actually turns off the screen and switches to a low power consumption mode. It is still running, but only just. This means that it can then be quickly woken so that you can carry on working in a couple of seconds, rather than waiting up to a minute for a normal boot up from cold.

MacBook owners have another way to put their laptop to sleep and this is by simply closing the lid. Some MacBooks have a flashing LED to show that they are in sleep mode, but not all do. Open the lid and the MacBook wakes up. 

Another way to put the Mac to sleep is to press Command+Option+Power button. However, it is easy to muddle this up with other commands like Command+Ctrl+Power button, which forces the Mac to restart.

What you may not be aware of is that iMacs and MacBooks use different sleep modes. An iMac uses sleep mode 0 and a MacBook uses sleep mode 3. There is another sleep mode, 25, that is not used by any Macs, but you can set it if you want to. You can also use the iMac sleep mode on a MacBook and MacBook sleep mode on an iMac.

It all sounds very confusing, but really it is quite straightforward.

Sleep mode 0

This is the default setting on iMacs and in this mode the computer is put into a low power state. The screen is turned off, the disk stops spinning (if it is a mechanical one), the CPU slows right down and so on. Every component runs in its lowest power mode, but it is still running and the contents of memory are retained.

When you press a key, the Mac wakes up all the components, which resume their normal power state. You can then continue working exactly where you left off.

This mode is used by iMacs because they are plugged into the mains power and this is assumed to be stable and permanently available. If this mode were to be used on a MacBook, sooner or later the battery would drain and eventually power would be lost, the contents of memory would be lost, and so would every app you were using.

Sleep mode 0 is the fastest sleep mode. It is quickest to enter and quickest to resume. If you are sure your MacBook battery will not completely run down, setting sleep mode 0 will be faster than normal sleep mode. As long as you wake it up before the battery dies, you will be OK.

Sleep mode 3

This sleep mode is designed to get around the problem of the battery draining and you losing all your work in any applications that are open. When a MacBook goes into sleep mode, it saves the current computer state to the disk drive. That is everything in memory, the apps you are using, the windows that are open and the documents being edited.

Once this disk backup has been made, which adds several seconds to the process, the MacBook then goes into sleep mode like an iMac. As long as there is battery power, the MacBook can instantly resume.

If the battery runs out and the MacBook loses power, you can plug in the power cable and start the Mac  by pressing the power button. It will resume from sleep mode by loading everything from disk. The exact computer state is restored from the backup and you can carry on where you left off. Restoring that disk backup takes a lot longer than resuming from memory. It works, but it is very slow in comparison.

Suppose you live in an area where the mains power is unstable. Your iMac could lose mains power while in sleep mode and you could lose your work in any open applications. Sleep mode 3 would be better in this case because it saves a backup to disk. If the power is cut, the iMac will resume from sleep when power is restored by loading the disk backup.

One disadvantage of sleep mode 3 is that a file on disk the same size as the RAM in the iMac or MacBook is created. So if you have 8GB of RAM, then 8GB of disk space is consumed in sleep mode. That could be inconvenient if you have a small SSD.

Sleep mode 25

This starts off like sleep mode 3 and the current computer state is saved to the disk drive. The iMac or MacBook then shuts down and powers off. When you resume from sleep by pressing the power button, it reloads everything from disk and lets you carry on where you left off.

Saving memory to disk uses disk space and is slow. Restoring everything from disk is also slow. The advantage for MacBook users though, is that no battery power is required during sleep mode because the computer is switched off. The MacBook could sleep for a week or a month, you could switch back on and carry on exactly where you left off.

SSDs are much faster than mechanical disk drives, so sleep mode 25 is not as slow. The disadvantage is the disk space required.

Set the sleep mode

The way to set these three sleep modes is by entering commands at the Terminal command prompt. Go to the Applications folder, open the Utilities folder and run

At the command prompt, enter one of the following commands:

sudo pmset -a hibernatemode 0
sudo pmset -a hibernatemode 3
sudo pmset -a hibernatemode 25

Choose the best mode bearing in mind the pros and cons described above.

sudo = admin mode - enter your password
pmset = the command to use
-a = all power modes (battery, mains power etc.)
hibernatemode = sleep mode
0, 3, 25 = the mode to use

Don’t try any other modes. These are the only three you should use.



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