Every few months I wonder “why is my Mac taking forever to wake up?” and end up googling pmset again. Here’s the cheat sheet I should’ve written years ago.
Check current settings#
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| # View all power management settings
pmset -g
# Check hibernate mode specifically
pmset -g | grep hibernatemode
# View current sleep settings
pmset -g custom
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Hibernate modes explained#
| Mode | Name | Behavior | RAM | Disk | Speed |
|---|
| 0 | Regular sleep | RAM only | ✓ | ✗ | Fast wake |
| 3 | Safe sleep | RAM + Disk backup | ✓ | ✓ | Fast wake, safe on power loss |
| 25 | Hibernation | Disk only | ✗ | ✓ | Slow wake, saves battery |
Mode 0 - Old-school sleep. Contents stay in RAM. Fast wake, but you lose everything if battery dies.
Mode 3 - Default on MacBooks. Writes RAM to disk as backup, keeps RAM powered. Best of both worlds - fast wake, but safe if battery dies.
Mode 25 - True hibernation like Windows. RAM powered off completely, everything written to disk. Slowest wake, but uses almost no battery.
Change hibernate mode#
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| # Set to regular sleep (fast wake, no disk backup)
sudo pmset -a hibernatemode 0
# Set to safe sleep (default on MacBooks)
sudo pmset -a hibernatemode 3
# Set to full hibernation (slowest wake, saves most battery)
sudo pmset -a hibernatemode 25
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Note: -a applies to all power sources (battery and AC). Use -b for battery only or -c for AC only.
Common scenarios#
Faster wake times (trade safety for speed)#
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| sudo pmset -a hibernatemode 0
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Maximum battery savings#
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| sudo pmset -a hibernatemode 25
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Restore defaults#
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| sudo pmset -a hibernatemode 3
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| # Disable sleep entirely
sudo pmset -a sleep 0
# Sleep after 10 minutes on battery
sudo pmset -b sleep 10
# Prevent sleep when display is off
sudo pmset -a disablesleep 1
# Show all settings
pmset -g custom
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Troubleshooting#
Remove sleep image file (reclaim space)#
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| # Check sleep image size
ls -lh /var/vm/sleepimage
# Remove it (recreated automatically)
sudo rm /var/vm/sleepimage
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Reset power management to defaults#
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| sudo pmset -a restoredefaults
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Pro tip: Mode 3 is default for good reason - it’s the sweet spot between wake speed and safety. Only change it if you have specific needs like saving every drop of battery or need millisecond-faster wake times.