Mac Sleep Settings for Performance and Battery Life

Your Mac's sleep mode is a low-power state that gives both the battery and the processor a break. From the outside, it seems like all sleep modes are the same, but Apple has implemented several types that affect different parts of the computer and how they return to work.

Here's what you need to know about sleep mode on your Mac.

Types of Sleep Mode in Macs

Apple supports three main types of sleep modes for desktops and portables. The three modes are Sleep, Hibernation, and Safe Sleep, and they each work slightly differently.

• In Sleep, the Mac's RAM stays on while it's sleeping. The Mac can wake up quickly because there's no need to load anything from the hard drive. This is the default sleep mode for desktop Macs.
• In Hibernation, the computer copies the contents of RAM to your drive before the Mac enters sleep. Once the Mac is sleeping, it removes power from the RAM. When you wake the Mac up, the startup drive must first write the data back, so wake time is a bit slower. Hibernation is the default sleep mode for portables released before 2005.
• In Safe Sleep, the Mac copies RAM contents to the startup drive before the Mac enters sleep, but the RAM remains powered while the Mac is sleeping. Wake time is fast because the RAM still contains the necessary info. Writing the RAM's contents to the startup drive is a safeguard. Should something happen, such as battery failure, you can still recover your data.

Find Out Which Sleep Mode Your Mac Uses

You can look at which sleep mode your computer uses by entering a command into the Terminal application. Here's what to do.

1. Open the Terminal application. It's in the Utilities folder under Applications.

2. Enter the following command at the prompt:

   pmset -g | grep hibernatemode
   

3. You should see one of the following responses:

   • hibernatemode 0: normal sleep; this is the default setting if you're using a desktop computer.
   • hibernatemode 1: hibernate mode; this is the default for pre-2005 laptops.
   • hibernatemode 3: safe sleep; this is the default for laptops made after 2005.
   • hibernatemode 25: hibernate mode; a setting compatible with post-2005 laptops.

   Hibernatemode 25 can maximize battery runtime, but it does so by taking longer to enter hibernation mode and to wake up. It also moves inactive memory to disk before hibernation occurs to create a smaller memory footprint. When your Mac wakes from sleep, it doesn't restore the inactive memory right away. Apps may take longer to load after your Mac wakes up.

Standby Mode Is Another Option

Macs can also enter a standby mode to conserve the battery's charge. A laptop can remain in this state for up to 30 days under ideal conditions. Most users with batteries in reasonable shape and fully charged could see 15 to 20 days of standby power.

Mac computers from 2013 and later support standby operations. They enter standby automatically after they've been asleep for three hours and have no external connections such as USB, Thunderbolt, or SD cards.

Exit standby by opening the lid on your Mac laptop or tapping any key, plugging in the power adapter, clicking the mouse or trackpad, or plugging in a display.

Changing Your Mac’s Sleep Mode

You can change the sleep mode your Mac is using, but if you try to force an unsupported sleep mode, it may cause your computer to lose data when sleeping. Even worse, you may end up with a device that won't wake up, in which case, you'll have to remove the battery and then reinstall it and the operating system, if you Mac has a removeable battery.

If your Mac isn't a pre-2005 laptop or you want to make the change anyway, enter the following command into Terminal:

sudo pmset -a hibernatemode X

Replace X with the number 0, 1, 3, or 25, depending on which sleep mode you want to use. You need your administrator password to complete the change.