How to Use macOS Hibernate Mode and Sleep on a Mac

Looking to save a maximum of energy and make sure your data is safe? Want sleep and wake to be immediate and save time? Find here what you need to know about sleep vs. macOS hibernate mode on a Mac, and how to choose between the two (or a combination) using hibernatemode.

First, Knowing This Will Help You Sleep Better

You can trust your sleep to the spindles.

During phase 2 sleep (which is typically the major part of sleep), one pattern commonly seen in EEGs measuring electrical brain activity is a K-complex followed by a sleep spindle. The K-complex occurs when you hear a noise, for example, and the sleep spindle‘s one proposed function is altering how this noise information is processed—so you don’t wake up.

So, no need to go overboard with sleep hygiene and banish all potential disruptions. You can trust your sleep to the spindles.

On your Mac, you can trust its sleep to the hard disk’s spindles—or to memory, of course. Let’s find out more:

How to Understand macOS Hibernate Mode vs. Sleep on a Mac

The main difference between Mac “sleep” and “hibernate” is where data is stored:

• Sleep saves the Mac’s state in RAM memory.
  This memory is fast to access but requires power to keep remembering.
• Hibernate saves the state to persistent hard-disk storage.
  The data is much slower to write and read, so both going to sleep and waking takes longer, but the disk needs no power to hold the data, so you can wake a Mac from hibernation after weeks or months.

	Sleep	Hibernation
Speed going to sleep	Immediate	Slow
Speed waking	Faster	Fast
Power saving	Substantial	Maximum
Data safety	Limited	Maximum

Learn about your Mac’s memory usage: How to Interpret Memory in Mac Activity Monitor

How the Sleep vs. Hibernate Mode Settings Work on macOS

There is one more option for power saving in addition to “sleep” vs. “hibernate” on a Mac (set using hibernatemode):

• Hibernatemode 0 is pure sleep.
  The system state is saved to memory, and the system only wakes from memory. If the computer loses power while asleep, it has to reboot and data not saved to disk is lost.
  This is the default for desktop computers (such as Mac Pro and iMac).
• Hibernatemode 25 is pure hibernation:
  The current state is saved to disk when the computer goes to sleep, and memory is turned off. Waking happens from disk only. While slow, this mode saves most power and ensures all data is saved to disk before sleep.
• Hibernatemode 3 is both sleep and hibernation:
  The system state is saved to both disk and memory, and the computer wakes from memory if available or disk if memory has been lost (because, say, the battery was empty and the system had to power down).
  This is the default for mobile computers (such as MacBook Airs).

As an additional twist, macOS can start in Hibernatemode 0 and switch to mode 25 after a while to save power. By default, macOS goes into hibernation (mode 25)

• after 3 hours with less than 50% of batter left
• and 24 hours with 50% battery left or more.

Settings for which mode to use, and when the system goes into hibernation can be changed for battery, power supply and UPS separately.

How to Change macOS Sleep and Hibernate Mode Settings for your Mac

Examples

sudo pmset -c hibernatemode 3 enables hybrid hibernation for wall power.
sudo pmset -a standbydelayhigh 10800 lets the system hibernate after 3 hours no matter the power supply (-a is for all).

How to Hibernate (or Sleep) a Mac

You can easily hibernate (or sleep) your Mac using keyboard shortcut, menu and Terminal.

(How to understand sleep vs. hibernate on a Mac tested with macOS Sonoma 14.3, Ventura 13.1, Monterey 12.0, and Big Sur 11.3; updated February 2024)